Handle race condition closing job stdin

This race condition is there for any key press, but it's greatly
exaggerated by Vim's default one second timeout on Escape.  This delay
also disqualifies Escape as the official interface to this feature, but
leave it as a DWIM alternative to CTRL-D for now.

Closes https://github.com/tpope/vim-fugitive/issues/1722

autoload/fugitive.vim

@@ -2566,6 +2566,19 @@ function! s:RunSend(job, str) abort
   endtry
 endfunction
 
+function! s:RunCloseIn(job) abort
+  try
+    if type(a:job) ==# type(0)
+      call chanclose(a:job, 'stdin')
+    else
+      call ch_close_in(a:job)
+    endif
+    return 1
+  catch /^Vim\%((\a\+)\)\=:E90[06]:/
+    return 0
+  endtry
+endfunction
+
 function! s:RunEcho(tmp) abort
   if !has_key(a:tmp, 'echo')
     return
@@ -2605,12 +2618,7 @@ function! s:RunWait(state, tmp, job, ...) abort
           let c = type(c) == type(0) ? nr2char(c) : c
           if c ==# "\<C-D>" || c ==# "\<Esc>"
             let a:state.closed_in = 1
-            if type(a:job) ==# type(0)
+            let can_pedit = s:RunCloseIn(a:job) && exists('*setbufline')
-              call chanclose(a:job, 'stdin')
-            else
-              call ch_close_in(a:job)
-            endif
-            let can_pedit = exists('*setbufline')
             for winnr in range(1, winnr('$'))
               if getwinvar(winnr, '&previewwindow') && getbufvar(winbufnr(winnr), '&modified')
                 let can_pedit = 0