sequencer: print autostash messages to stderr

The rebase messages are printed to stderr traditionally. However due
to a bug introduced in 587947750bd (rebase: implement --[no-]autostash
and rebase.autostash, 2013-05-12) which was faithfully copied when
reimplementing parts of the interactive rebase in the sequencer the
autostash messages are printed to stdout instead.

It is time to fix that: let's print the autostash messages to stderr
instead of stdout.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/git-rebase.sh b/git-rebase.sh
index 48d7c5d..3b0448d 100755
--- a/git-rebase.sh
+++ b/git-rebase.sh
@@ -165,14 +165,14 @@
 		stash_sha1=$(cat "$state_dir/autostash")
 		if git stash apply $stash_sha1 2>&1 >/dev/null
 		then
-			echo "$(gettext 'Applied autostash.')"
+			echo "$(gettext 'Applied autostash.')" >&2
 		else
 			git stash store -m "autostash" -q $stash_sha1 ||
 			die "$(eval_gettext "Cannot store \$stash_sha1")"
 			gettext 'Applying autostash resulted in conflicts.
 Your changes are safe in the stash.
 You can run "git stash pop" or "git stash drop" at any time.
-'
+' >&2
 		fi
 	fi
 }