Ensure open folds after expanding inline diff

autoload/fugitive.vim

@@ -3485,6 +3485,9 @@ function! s:StageInline(mode, ...) abort
     if len(diff)
       setlocal modifiable noreadonly
       silent call append(lnum, diff)
+      if foldclosed(lnum+1)
+        silent exe (lnum+1) . ',' . (lnum+len(diff)) . 'foldopen!'
+      endif
       let b:fugitive_expanded[info.section][info.filename] = [start, len(diff)]
       setlocal nomodifiable readonly nomodified
     endif