Use keepalt for diff maps

Resolves: tpope#2336

autoload/fugitive.vim

@@ -5036,19 +5036,19 @@ function! s:StageDiff(diff) abort
     return 'Git --paginate diff --no-ext-diff'
   elseif len(info.paths) > 1
     execute 'Gedit' . prefix s:fnameescape(':0:' . info.paths[0])
-    return a:diff . '! @:'.s:fnameescape(info.paths[1])
+    return 'keepalt ' . a:diff . '! @:'.s:fnameescape(info.paths[1])
   elseif info.section ==# 'Staged' && info.sigil ==# '-'
     execute 'Gedit' prefix s:fnameescape(':0:'.info.paths[0])
-    return a:diff . '! :0:%'
+    return 'keepalt ' . a:diff . '! :0:%'
   elseif info.section ==# 'Staged'
     execute 'Gedit' prefix s:fnameescape(':0:'.info.paths[0])
-    return a:diff . '! @:%'
+    return 'keepalt ' . a:diff . '! @:%'
   elseif info.sigil ==# '-'
     execute 'Gedit' prefix s:fnameescape(':0:'.info.paths[0])
-    return a:diff . '! :(top)%'
+    return 'keepalt ' . a:diff . '! :(top)%'
   else
     execute 'Gedit' prefix s:fnameescape(':(top)'.info.paths[0])
-    return a:diff . '!'
+    return 'keepalt ' . a:diff . '!'
   endif
 endfunction
 
@@ -8062,10 +8062,10 @@ function! fugitive#MapJumps(...) abort
       endif
 
       call s:Map('n', 'D', ":echoerr 'fugitive: D has been removed in favor of dd'<CR>", '<silent><unique>')
-      call s:Map('n', 'dd', ":<C-U>call fugitive#DiffClose()<Bar>Gdiffsplit!<CR>", '<silent>')
-      call s:Map('n', 'dh', ":<C-U>call fugitive#DiffClose()<Bar>Ghdiffsplit!<CR>", '<silent>')
-      call s:Map('n', 'ds', ":<C-U>call fugitive#DiffClose()<Bar>Ghdiffsplit!<CR>", '<silent>')
-      call s:Map('n', 'dv', ":<C-U>call fugitive#DiffClose()<Bar>Gvdiffsplit!<CR>", '<silent>')
+      call s:Map('n', 'dd', ":<C-U>call fugitive#DiffClose()<Bar>keepalt Gdiffsplit!<CR>", '<silent>')
+      call s:Map('n', 'dh', ":<C-U>call fugitive#DiffClose()<Bar>keepalt Ghdiffsplit!<CR>", '<silent>')
+      call s:Map('n', 'ds', ":<C-U>call fugitive#DiffClose()<Bar>keepalt Ghdiffsplit!<CR>", '<silent>')
+      call s:Map('n', 'dv', ":<C-U>call fugitive#DiffClose()<Bar>keepalt Gvdiffsplit!<CR>", '<silent>')
       call s:Map('n', 'd?', ":<C-U>help fugitive_d<CR>", '<silent>')
 
     else