rebase: factor out clean work tree check

Remove the check for clean work tree from git-rebase--interactive.sh and
rely on the check in git-rebase.sh.

Signed-off-by: Martin von Zweigbergk <martin.von.zweigbergk@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

git-rebase--interactive.sh

@@ -753,8 +753,6 @@ esac
 git var GIT_COMMITTER_IDENT >/dev/null ||
 	die "You need to set your committer info first"
 
-require_clean_work_tree "rebase" "Please commit or stash them."
-
 run_pre_rebase_hook "$upstream_arg" "$@"
 
 comment_for_reflog start

git-rebase.sh

@@ -511,10 +511,10 @@ case "$#" in
 esac
 orig_head=$branch
 
-test "$type" = interactive && run_interactive_rebase "$@"
-
 require_clean_work_tree "rebase" "Please commit or stash them."
 
+test "$type" = interactive && run_interactive_rebase "$@"
+
 # Now we are rebasing commits $upstream..$branch (or with --root,
 # everything leading up to $branch) on top of $onto