no need to shellescape here

autoload/vundle/installer.vim

@@ -57,7 +57,7 @@ func! s:helptags(rtp) abort
 endf
 
 func! s:sync(bang, bundle) abort
-  let git_dir = shellescape(expand(a:bundle.path().'/.git'))
+  let git_dir = expand(a:bundle.path().'/.git')
   if isdirectory(git_dir)
     if !(a:bang) | return 0 | endif
     let cmd = 'cd '.shellescape(a:bundle.path()).' && git pull'