diff --git a/.gitignore b/.gitignore
index 5be8b98..911e292 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,4 @@
 .netrwhist
 .vim/
 plugged/
+plug.vim.old
diff --git a/autoload/plug.vim b/autoload/plug.vim
index 7914bfe..865ce3f 100644
--- a/autoload/plug.vim
+++ b/autoload/plug.vim
@@ -25,7 +25,7 @@
 "   Plug 'scrooloose/nerdtree', { 'on':  'NERDTreeToggle' }
 "   Plug 'tpope/vim-fireplace', { 'for': 'clojure' }
 "
-"   " Using a non-master branch
+"   " Using a non-default branch
 "   Plug 'rdnetto/YCM-Generator', { 'branch': 'stable' }
 "
 "   " Using a tagged release; wildcard allowed (requires git 1.9.2 or above)
@@ -106,7 +106,7 @@ if s:is_win && &shellslash
 else
   let s:me = resolve(expand('<sfile>:p'))
 endif
-let s:base_spec = { 'branch': 'master', 'frozen': 0 }
+let s:base_spec = { 'branch': '', 'frozen': 0 }
 let s:TYPE = {
 \   'string':  type(''),
 \   'list':    type([]),
@@ -116,6 +116,90 @@ let s:TYPE = {
 let s:loaded = get(s:, 'loaded', {})
 let s:triggers = get(s:, 'triggers', {})
 
+function! s:isabsolute(dir) abort
+  return a:dir =~# '^/' || (has('win32') && a:dir =~? '^\%(\\\|[A-Z]:\)')
+endfunction
+
+function! s:git_dir(dir) abort
+  let gitdir = s:trim(a:dir) . '/.git'
+  if isdirectory(gitdir)
+    return gitdir
+  endif
+  if !filereadable(gitdir)
+    return ''
+  endif
+  let gitdir = matchstr(get(readfile(gitdir), 0, ''), '^gitdir: \zs.*')
+  if len(gitdir) && !s:isabsolute(gitdir)
+    let gitdir = a:dir . '/' . gitdir
+  endif
+  return isdirectory(gitdir) ? gitdir : ''
+endfunction
+
+function! s:git_origin_url(dir) abort
+  let gitdir = s:git_dir(a:dir)
+  let config = gitdir . '/config'
+  if empty(gitdir) || !filereadable(config)
+    return ''
+  endif
+  return matchstr(join(readfile(config)), '\[remote "origin"\].\{-}url\s*=\s*\zs\S*\ze')
+endfunction
+
+function! s:git_revision(dir) abort
+  let gitdir = s:git_dir(a:dir)
+  let head = gitdir . '/HEAD'
+  if empty(gitdir) || !filereadable(head)
+    return ''
+  endif
+
+  let line = get(readfile(head), 0, '')
+  let ref = matchstr(line, '^ref: \zs.*')
+  if empty(ref)
+    return line
+  endif
+
+  if filereadable(gitdir . '/' . ref)
+    return get(readfile(gitdir . '/' . ref), 0, '')
+  endif
+
+  if filereadable(gitdir . '/packed-refs')
+    for line in readfile(gitdir . '/packed-refs')
+      if line =~# ' ' . ref
+        return matchstr(line, '^[0-9a-f]*')
+      endif
+    endfor
+  endif
+
+  return ''
+endfunction
+
+function! s:git_local_branch(dir) abort
+  let gitdir = s:git_dir(a:dir)
+  let head = gitdir . '/HEAD'
+  if empty(gitdir) || !filereadable(head)
+    return ''
+  endif
+  let branch = matchstr(get(readfile(head), 0, ''), '^ref: refs/heads/\zs.*')
+  return len(branch) ? branch : 'HEAD'
+endfunction
+
+function! s:git_origin_branch(spec)
+  if len(a:spec.branch)
+    return a:spec.branch
+  endif
+
+  " The file may not be present if this is a local repository
+  let gitdir = s:git_dir(a:spec.dir)
+  let origin_head = gitdir.'/refs/remotes/origin/HEAD'
+  if len(gitdir) && filereadable(origin_head)
+    return matchstr(get(readfile(origin_head), 0, ''),
+                  \ '^ref: refs/remotes/origin/\zs.*')
+  endif
+
+  " The command may not return the name of a branch in detached HEAD state
+  let result = s:lines(s:system('git symbolic-ref --short HEAD', a:spec.dir))
+  return v:shell_error ? '' : result[-1]
+endfunction
+
 if s:is_win
   function! s:plug_call(fn, ...)
     let shellslash = &shellslash
@@ -646,25 +730,25 @@ function! s:parse_options(arg)
     endif
     let opts.tag = a:arg
   elseif type == s:TYPE.dict
-    call extend(opts, a:arg)
     for opt in ['branch', 'tag', 'commit', 'rtp', 'dir', 'as']
-      if has_key(opts, opt)
-      \ && (type(opts[opt]) != s:TYPE.string || empty(opts[opt]))
+      if has_key(a:arg, opt)
+      \ && (type(a:arg[opt]) != s:TYPE.string || empty(a:arg[opt]))
         throw printf(opt_errfmt, opt, 'string')
       endif
     endfor
     for opt in ['on', 'for']
-      if has_key(opts, opt)
-      \ && type(opts[opt]) != s:TYPE.list
-      \ && (type(opts[opt]) != s:TYPE.string || empty(opts[opt]))
+      if has_key(a:arg, opt)
+      \ && type(a:arg[opt]) != s:TYPE.list
+      \ && (type(a:arg[opt]) != s:TYPE.string || empty(a:arg[opt]))
         throw printf(opt_errfmt, opt, 'string or list')
       endif
     endfor
-    if has_key(opts, 'do')
-      \ && type(opts.do) != s:TYPE.funcref
-      \ && (type(opts.do) != s:TYPE.string || empty(opts.do))
+    if has_key(a:arg, 'do')
+      \ && type(a:arg.do) != s:TYPE.funcref
+      \ && (type(a:arg.do) != s:TYPE.string || empty(a:arg.do))
         throw printf(opt_errfmt, 'do', 'string or funcref')
     endif
+    call extend(opts, a:arg)
     if has_key(opts, 'dir')
       let opts.dir = s:dirpath(s:plug_expand(opts.dir))
     endif
@@ -720,7 +804,7 @@ function! s:syntax()
   syn match plugNumber /[0-9]\+[0-9.]*/ contained
   syn match plugBracket /[[\]]/ contained
   syn match plugX /x/ contained
-  syn match plugDash /^-/
+  syn match plugDash /^-\{1}\ /
   syn match plugPlus /^+/
   syn match plugStar /^*/
   syn match plugMessage /\(^- \)\@<=.*/
@@ -738,6 +822,7 @@ function! s:syntax()
   syn match plugError /^x.*/
   syn region plugDeleted start=/^\~ .*/ end=/^\ze\S/
   syn match plugH2 /^.*:\n-\+$/
+  syn match plugH2 /^-\{2,}/
   syn keyword Function PlugInstall PlugStatus PlugUpdate PlugClean
   hi def link plug1       Title
   hi def link plug2       Repeat
@@ -991,10 +1076,10 @@ endfunction
 
 function! s:checkout(spec)
   let sha = a:spec.commit
-  let output = s:system(['git', 'rev-parse', 'HEAD'], a:spec.dir)
-  if !v:shell_error && !s:hash_match(sha, s:lines(output)[0])
+  let output = s:git_revision(a:spec.dir)
+  if !empty(output) && !s:hash_match(sha, s:lines(output)[0])
     let output = s:system(
-          \ 'git fetch --depth 999999 && git checkout '.plug#shellescape(sha).' --', a:spec.dir)
+          \ 'git -c credential.helper= fetch --depth 999999 && git checkout '.plug#shellescape(sha).' --', a:spec.dir)
   endif
   return output
 endfunction
@@ -1206,7 +1291,7 @@ function! s:update_finish()
         call s:log4(name, 'Checking out '.tag)
         let out = s:system('git checkout -q '.plug#shellescape(tag).' -- 2>&1', spec.dir)
       else
-        let branch = get(spec, 'branch', 'master')
+        let branch = s:git_origin_branch(spec)
         call s:log4(name, 'Merging origin/'.s:esc(branch))
         let out = s:system('git checkout -q '.plug#shellescape(branch).' -- 2>&1'
               \. (has_key(s:update.new, name) ? '' : ('&& git merge --ff-only '.plug#shellescape('origin/'.branch).' 2>&1')), spec.dir)
@@ -1762,7 +1847,7 @@ class Plugin(object):
       self.write(Action.UPDATE, self.name, ['Updating ...'])
       callback = functools.partial(self.write, Action.UPDATE, self.name)
       fetch_opt = '--depth 99999999' if self.tag and os.path.isfile(os.path.join(self.args['dir'], '.git/shallow')) else ''
-      cmd = 'git fetch {0} {1} 2>&1'.format(fetch_opt, G_PROGRESS)
+      cmd = 'git -c credential.helper= fetch {0} {1} 2>&1'.format(fetch_opt, G_PROGRESS)
       com = Command(cmd, self.args['dir'], G_TIMEOUT, callback)
       result = com.execute(G_RETRIES)
       self.write(Action.DONE, self.name, result[-1:])
@@ -2070,7 +2155,7 @@ function! s:update_ruby()
                 if pull
                   log.call name, 'Updating ...', :update
                   fetch_opt = (tag && File.exist?(File.join(dir, '.git/shallow'))) ? '--depth 99999999' : ''
-                  bt.call "#{chdir} && git fetch #{fetch_opt} #{progress} 2>&1", name, :update, nil
+                  bt.call "#{chdir} && git -c credential.helper= fetch #{fetch_opt} #{progress} 2>&1", name, :update, nil
                 else
                   [true, skip]
                 end
@@ -2211,18 +2296,17 @@ endfunction
 function! s:git_validate(spec, check_branch)
   let err = ''
   if isdirectory(a:spec.dir)
-    let result = s:lines(s:system('git rev-parse --abbrev-ref HEAD 2>&1 && git config -f .git/config remote.origin.url', a:spec.dir))
+    let result = [s:git_local_branch(a:spec.dir), s:git_origin_url(a:spec.dir)]
     let remote = result[-1]
-    if v:shell_error
+    if empty(remote)
       let err = join([remote, 'PlugClean required.'], "\n")
     elseif !s:compare_git_uri(remote, a:spec.uri)
       let err = join(['Invalid URI: '.remote,
                     \ 'Expected:    '.a:spec.uri,
                     \ 'PlugClean required.'], "\n")
     elseif a:check_branch && has_key(a:spec, 'commit')
-      let result = s:lines(s:system('git rev-parse HEAD 2>&1', a:spec.dir))
-      let sha = result[-1]
-      if v:shell_error
+      let sha = s:git_revision(a:spec.dir)
+      if empty(sha)
         let err = join(add(result, 'PlugClean required.'), "\n")
       elseif !s:hash_match(sha, a:spec.commit)
         let err = join([printf('Invalid HEAD (expected: %s, actual: %s)',
@@ -2230,8 +2314,9 @@ function! s:git_validate(spec, check_branch)
                       \ 'PlugUpdate required.'], "\n")
       endif
     elseif a:check_branch
-      let branch = result[0]
+      let current_branch = result[0]
       " Check tag
+      let origin_branch = s:git_origin_branch(a:spec)
       if has_key(a:spec, 'tag')
         let tag = s:system_chomp('git describe --exact-match --tags HEAD 2>&1', a:spec.dir)
         if a:spec.tag !=# tag && a:spec.tag !~ '\*'
@@ -2239,14 +2324,14 @@ function! s:git_validate(spec, check_branch)
                 \ (empty(tag) ? 'N/A' : tag), a:spec.tag)
         endif
       " Check branch
-      elseif a:spec.branch !=# branch
+      elseif origin_branch !=# current_branch
         let err = printf('Invalid branch: %s (expected: %s). Try PlugUpdate.',
-              \ branch, a:spec.branch)
+              \ current_branch, origin_branch)
       endif
       if empty(err)
         let [ahead, behind] = split(s:lastline(s:system([
         \ 'git', 'rev-list', '--count', '--left-right',
-        \ printf('HEAD...origin/%s', a:spec.branch)
+        \ printf('HEAD...origin/%s', origin_branch)
         \ ], a:spec.dir)), '\t')
         if !v:shell_error && ahead
           if behind
@@ -2254,11 +2339,11 @@ function! s:git_validate(spec, check_branch)
             " pushable (and probably not that messed up).
             let err = printf(
                   \ "Diverged from origin/%s (%d commit(s) ahead and %d commit(s) behind!\n"
-                  \ .'Backup local changes and run PlugClean and PlugUpdate to reinstall it.', a:spec.branch, ahead, behind)
+                  \ .'Backup local changes and run PlugClean and PlugUpdate to reinstall it.', origin_branch, ahead, behind)
           else
             let err = printf("Ahead of origin/%s by %d commit(s).\n"
                   \ .'Cannot update until local changes are pushed.',
-                  \ a:spec.branch, ahead)
+                  \ origin_branch, ahead)
           endif
         endif
       endif
@@ -2588,20 +2673,23 @@ function! s:diff()
     endif
     call s:append_ul(2, origin ? 'Pending updates:' : 'Last update:')
     for [k, v] in plugs
-      let range = origin ? '..origin/'.v.branch : 'HEAD@{1}..'
-      let cmd = ['git', 'log', '--graph', '--color=never']
-      if s:git_version_requirement(2, 10, 0)
-        call add(cmd, '--no-show-signature')
-      endif
-      call extend(cmd, ['--pretty=format:%x01%h%x01%d%x01%s%x01%cr', range])
-      if has_key(v, 'rtp')
-        call extend(cmd, ['--', v.rtp])
-      endif
-      let diff = s:system_chomp(cmd, v.dir)
-      if !empty(diff)
-        let ref = has_key(v, 'tag') ? (' (tag: '.v.tag.')') : has_key(v, 'commit') ? (' '.v.commit) : ''
-        call append(5, extend(['', '- '.k.':'.ref], map(s:lines(diff), 's:format_git_log(v:val)')))
-        let cnts[origin] += 1
+      let branch = s:git_origin_branch(v)
+      if len(branch)
+        let range = origin ? '..origin/'.branch : 'HEAD@{1}..'
+        let cmd = ['git', 'log', '--graph', '--color=never']
+        if s:git_version_requirement(2, 10, 0)
+          call add(cmd, '--no-show-signature')
+        endif
+        call extend(cmd, ['--pretty=format:%x01%h%x01%d%x01%s%x01%cr', range])
+        if has_key(v, 'rtp')
+          call extend(cmd, ['--', v.rtp])
+        endif
+        let diff = s:system_chomp(cmd, v.dir)
+        if !empty(diff)
+          let ref = has_key(v, 'tag') ? (' (tag: '.v.tag.')') : has_key(v, 'commit') ? (' '.v.commit) : ''
+          call append(5, extend(['', '- '.k.':'.ref], map(s:lines(diff), 's:format_git_log(v:val)')))
+          let cnts[origin] += 1
+        endif
       endif
       let bar .= '='
       call s:progress_bar(2, bar, len(total))
@@ -2663,7 +2751,7 @@ function! s:snapshot(force, ...) abort
   let names = sort(keys(filter(copy(g:plugs),
         \'has_key(v:val, "uri") && !has_key(v:val, "commit") && isdirectory(v:val.dir)')))
   for name in reverse(names)
-    let sha = s:system_chomp(['git', 'rev-parse', '--short', 'HEAD'], g:plugs[name].dir)
+    let sha = s:git_revision(g:plugs[name].dir)
     if !empty(sha)
       call append(anchor, printf("silent! let g:plugs['%s'].commit = '%s'", name, sha))
       redraw