Add debug command.

autoload/debug.vim

@@ -0,0 +1,59 @@
+function! debug#debug()
+  " Open a scratch buffer
+  vsplit __GitGutter_Debug__
+  normal! ggdG
+  setlocal buftype=nofile
+  setlocal bufhidden=delete
+  setlocal noswapfile
+
+  call debug#vim_version()
+  call debug#separator()
+
+  call debug#git_version()
+  call debug#separator()
+
+  call debug#option('shell')
+  call debug#option('shellcmdflag')
+  call debug#option('shellpipe')
+  call debug#option('shellquote')
+  call debug#option('shellredir')
+  call debug#option('shellslash')
+  call debug#option('shelltemp')
+  call debug#option('shelltype')
+  call debug#option('shellxescape')
+  call debug#option('shellxquote')
+endfunction
+
+
+function! debug#separator()
+  call debug#output('')
+endfunction
+
+function! debug#vim_version()
+  redir => version_info
+    silent execute 'version'
+  redir END
+  call debug#output(split(version_info, '\n')[0:2])
+endfunction
+
+function! debug#git_version()
+  let v = system('git --version')
+  call debug#output( substitute(v, '\n$', '', '') )
+endfunction
+
+function! debug#option(name)
+  if exists('+' . a:name)
+    let v = eval('&' . a:name)
+    call debug#output(a:name . '=' . v)
+    " redir => output
+    "   silent execute "verbose set " . a:name . "?"
+    " redir END
+    " call debug#output(a:name . '=' . output)
+  else
+    call debug#output(a:name . ' [n/a]')
+  end
+endfunction
+
+function! debug#output(text)
+  call append(line('$'), a:text)
+endfunction

plugin/gitgutter.vim

@@ -301,6 +301,7 @@ endfunction
 
 " }}}
 
+command GitGutterDebug call debug#debug()
 
 " Maps {{{