Handle .git in file system root

References https://github.com/tpope/vim-fugitive/issues/908

README.markdown

@@ -35,9 +35,15 @@ and you never get any warnings about the file changing outside Vim.
 making it like `git add` when called from a work tree file and like
 `git checkout` when called from the index or a blob in history.
 
-Use `:Gbrowse` to open the current file on GitHub, with optional line
-range (try it in visual mode!).  If your current repository isn't on
-GitHub, `git instaweb` will be spun up instead.
+Use `:Gbrowse` to open the current file on the web front-end of your favorite
+hosting provider, with optional line range (try it in visual mode!).  Built-in
+support is provided for `git instaweb`, and plugins are available for popular
+providers such as [GitHub][rhubarb.vim], [GitLab][fugitive-gitlab.vim], and
+[Bitbucket][fubitive.vim].
+
+[rhubarb.vim]: https://github.com/tpope/vim-rhubarb
+[fugitive-gitlab.vim]: https://github.com/shumphrey/fugitive-gitlab.vim
+[fubitive.vim]: https://github.com/tommcdo/vim-fubitive
 
 Add `%{fugitive#statusline()}` to `'statusline'` to get an indicator
 with the current branch in (surprise!) your statusline.
@@ -55,15 +61,13 @@ and `Git!` to open the output of a command in a temp file.
 
 ## Installation
 
-If you don't have a preferred installation method, I recommend
-installing [pathogen.vim](https://github.com/tpope/vim-pathogen), and
-then simply copy and paste:
+If you don't have a preferred installation method, one option is to install
+[pathogen.vim](https://github.com/tpope/vim-pathogen), and then copy
+and paste:
 
     cd ~/.vim/bundle
     git clone git://github.com/tpope/vim-fugitive.git
-
-Once help tags have been generated, you can view the manual with
-`:help fugitive`.
+    vim -u NONE -c "helptags vim-fugitive/doc" -c q
 
 If your Vim version is below 7.2, I recommend also installing
 [vim-git](https://github.com/tpope/vim-git) for syntax highlighting and

doc/fugitive.txt

@@ -57,24 +57,48 @@ that are part of Git repositories).
                         q     close status
                         r     reload status
                         S     |:Gvsplit|
+                        U     |:Git| checkout
+                        U     |:Git| checkout HEAD (staged files)
+                        U     |:Git| clean (untracked files)
+                        U     |:Git| rm (unmerged files)
 
                                                 *fugitive-:Gcommit*
 :Gcommit [args]         A wrapper around git-commit.  If there is nothing
                         to commit, |:Gstatus| is called instead.  Unless the
                         arguments given would skip the invocation of an editor
                         (e.g., -m), a split window will be used to obtain a
-                        commit message.  Write and close that window (:wq or
-                        |:Gwrite|) to finish the commit.  Unlike when running
-                        the actual git-commit command, it is possible (but
-                        unadvisable) to muck with the index with commands like
-                        git-add and git-reset while a commit message is
-                        pending.
+                        commit message, or a new tab if -v is given.  Write
+                        and close that window (:wq or |:Gwrite|) to finish the
+                        commit.  Unlike when running the actual git-commit
+                        command, it is possible (but unadvisable) to alter the
+                        index with commands like git-add and git-reset while a
+                        commit message is pending.
+
+                                                *fugitive-:Gmerge*
+:Gmerge [args]          Calls git-merge and loads errors and conflicted files
+                        into the quickfix list.  Opens a |:Gcommit| style
+                        split window for the commit message if the merge
+                        succeeds.  If called during a merge conflict, the
+                        conflicted files from the current index are loaded
+                        into the quickfix list.
+
+                                                *fugitive-:Gpull*
+:Gpull [args]           Like |:Gmerge|, but for git-pull.
+
+                                                *fugitive-:Gpush*
+:Gpush [args]           Invoke git-push, load the results into the quickfix
+                        list, and invoke |:cwindow| to reveal any errors.
+                        |:Dispatch| is used if available for asynchronous
+                        invocation.
+
+                                                *fugitive-:Gfetch*
+:Gfetch [args]          Like |:Gpush|, but for git-fetch.
 
                                                 *fugitive-:Ggrep*
-:Ggrep [args]           |:grep| with git-grep as 'grepprg'.
+:Ggrep[!] [args]        |:grep|[!] with git-grep as 'grepprg'.
 
                                                 *fugitive-:Glgrep*
-:Glgrep [args]          |:lgrep| with git-grep as 'grepprg'.
+:Glgrep[!] [args]       |:lgrep|[!] with git-grep as 'grepprg'.
 
                                                 *fugitive-:Glog*
 :Glog [args]            Load all previous revisions of the current file into
@@ -84,6 +108,11 @@ that are part of Git repositories).
                         previous commits rather than previous file revisions
                         are loaded.
 
+:{range}Glog [args]     Use git-log -L to load previous revisions of the given
+                        range of the current file into the quickfix list.  The
+                        cursor is positioned on the first line of the first
+                        diff hunk for each commit.
+
                                                 *fugitive-:Gllog*
 :Gllog [args]           Like |:Glog|, but use the location list instead of the
                         quickfix list.
@@ -152,7 +181,9 @@ that are part of Git repositories).
                         to the right or bottom, depending on 'diffopt' and
                         the width of the window relative to 'textwidth'.  Use
                         |do| and |dp| and write to the index file to simulate
-                        "git add --patch".
+                        "git add --patch". For the three-way diff, there is
+                        also d2o and d3o pulling the hunk to the middle from
+                        the left or the right window, respectively.
 
                                                 *fugitive-:Gsdiff*
 :Gsdiff [revision]      Like |:Gdiff|, but always split horizontally.
@@ -195,32 +226,38 @@ that are part of Git repositories).
 :[range]Gblame [flags]  Run git-blame on the given range.
 
                                                 *fugitive-:Gbrowse*
-:[range]Gbrowse         If the remote for the current branch is on GitHub,
-                        open the current file, blob, tree, commit, or tag
-                        (with git-web--browse) on GitHub.  Otherwise, open the
-                        current file, blob, tree, commit, or tag in
-                        git-instaweb (if you have issues, verify you can run
-                        "git instaweb" from a terminal).  If a range is given,
-                        it is appropriately appended to the URL as an anchor.
+:Gbrowse                Open the current file, blob, tree, commit, or tag
+                        in your browser at the upstream hosting provider.
+                        If a range is given, it is appropriately appended to
+                        the URL as an anchor.
 
-                        To use with GitHub FI, point g:fugitive_github_domains
-                        at a list of domains:
->
-                        let g:fugitive_github_domains = ['https://example.com']
-~
-:[range]Gbrowse!        Like :Gbrowse, but put the URL on the clipboard rather
-                        than opening it.
+                        Upstream providers can be added by installing an
+                        appropriate Vim plugin.  For example, GitHub can be
+                        supported by installing rhubarb.vim, available at
+                        <https://github.com/tpope/vim-rhubarb>.
 
-:[range]Gbrowse {revision}
-                        Like :Gbrowse, but for a given |fugitive-revision|.  A
+                        The hosting provider is determined by looking at the
+                        remote for the current or specified branch and falls
+                        back to "origin".  In the special case of a "."
+                        remote, a local instance of git-instaweb will be
+                        started and used.
+
+:Gbrowse {revision}     Like :Gbrowse, but for a given |fugitive-revision|.  A
                         useful value here is -, which ties the URL to the
                         latest commit rather than a volatile branch.
 
-:[range]Gbrowse [...]@{remote}
-                        Force using the given remote rather than the remote
+:Gbrowse [...]@{remote} Force using the given remote rather than the remote
                         for the current branch.  The remote is used to
                         determine which GitHub repository to link to.
 
+:{range}Gbrowse [args]  Appends an anchor to the URL that emphasizes the
+                        selected lines.  You almost certainly want to give a
+                        "-" argument in this case to force the URL to include
+                        an exact revision.
+
+:[range]Gbrowse! [args] Like :Gbrowse, but put the URL on the clipboard rather
+                        than opening it.
+
 MAPPINGS                                        *fugitive-mappings*
 
 These maps are available everywhere.