Add experimental behavior for X on commit line

Resolves: https://github.com/tpope/vim-fugitive/issues/1847

autoload/fugitive.vim

@@ -4804,9 +4804,13 @@ function! s:StageDelete(lnum1, lnum2, count) abort
 
   let err = ''
   let did_conflict_err = 0
+  let reset_commit = matchstr(getline(a:lnum1), '^Un\w\+ \%(to\| from\) \zs\S\+')
   try
     for info in s:Selection(a:lnum1, a:lnum2)
       if empty(info.paths)
+        if len(info.commit)
+          let reset_commit = info.commit . '^'
+        endif
         continue
       endif
       let sub = get(get(get(b:fugitive_files, info.section, {}), info.filename, {}), 'submodule')
@@ -4872,15 +4876,14 @@ function! s:StageDelete(lnum1, lnum2, count) abort
     let err .= '|echoerr ' . string(v:exception)
   endtry
   if empty(restore)
+    if len(reset_commit) && empty(err)
+      call feedkeys(':Git reset ' . reset_commit)
+    endif
     return err[1:-1]
   endif
   exe s:ReloadStatus()
   call s:StageReveal()
-  if len(restore)
-    return 'checktime|redraw|echomsg ' . string('To restore, ' . join(restore, '|')) . err
-  else
-    return 'checktime|redraw' . err
-  endif
+  return 'checktime|redraw|echomsg ' . string('To restore, ' . join(restore, '|')) . err
 endfunction
 
 function! s:StageIgnore(lnum1, lnum2, count) abort