Merge branch 'jk/filter-branch-require-clean-work-tree'

* jk/filter-branch-require-clean-work-tree:
  filter-branch: use require_clean_work_tree

Author: gitster

git-filter-branch.sh

@@ -108,9 +108,7 @@ OPTIONS_SPEC=
 . git-sh-setup
 
 if [ "$(is_bare_repository)" = false ]; then
-	git diff-files --ignore-submodules --quiet &&
-	git diff-index --cached --quiet HEAD -- ||
-	die "Cannot rewrite branch(es) with a dirty working directory."
+	require_clean_work_tree 'rewrite branches'
 fi
 
 tempdir=.git-rewrite