Fix write in index with guioptions=!

autoload/fugitive.vim

@@ -2258,6 +2258,10 @@ function! fugitive#FileWriteCmd(...) abort
     if commit !~# '^[0-3]$' || !v:cmdbang && (line("'[") != 1 || line("']") != line('$'))
       return "noautocmd '[,']write" . (v:cmdbang ? '!' : '') . ' ' . s:fnameescape(amatch)
     endif
+    if exists('+guioptions') && &guioptions =~# '!'
+      let guioptions = &guioptions
+      set guioptions-=!
+    endif
     silent execute "'[,']write !".fugitive#Prepare(dir, 'hash-object', '-w', '--stdin', '--').' > '.tmp
     let sha1 = readfile(tmp)[0]
     let old_mode = matchstr(s:SystemError([dir, 'ls-files', '--stage', '.' . file])[0], '^\d\+')
@@ -2275,6 +2279,9 @@ function! fugitive#FileWriteCmd(...) abort
       return 'echoerr '.string('fugitive: '.error)
     endif
   finally
+    if exists('guioptions')
+      let &guioptions = guioptions
+    endif
     call delete(tmp)
   endtry
 endfunction