revision walker: --cherry-pick is a limited operation

We used to rely on the fact that cherry-pick would trigger the code path
to set limited = 1 in handle_commit(), when an uninteresting commit was
encountered.

However, when cherry picking between two independent branches, i.e. when
there are no merge bases, and there is only linear development (which can
happen when you cvsimport a fork of a project), no uninteresting commit
will be encountered.

So set limited = 1 when --cherry-pick was asked for.

Noticed by Martin Bähr.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

revision.c

@@ -1024,6 +1024,7 @@ int setup_revisions(int argc, const char **argv, struct rev_info *revs, const ch
 			}
 			if (!strcmp(arg, "--cherry-pick")) {
 				revs->cherry_pick = 1;
+				revs->limited = 1;
 				continue;
 			}
 			if (!strcmp(arg, "--objects")) {

t/t6007-rev-list-cherry-pick-file.sh

@@ -40,4 +40,18 @@ test_expect_success '--cherry-pick bar does not come up empty' '
 	! test -z "$(git rev-list --left-right --cherry-pick B...C -- bar)"
 '
 
+test_expect_success '--cherry-pick with independent, but identical branches' '
+	git symbolic-ref HEAD refs/heads/independent &&
+	rm .git/index &&
+	echo Hallo > foo &&
+	git add foo &&
+	test_tick &&
+	git commit -m "independent" &&
+	echo Bello > foo &&
+	test_tick &&
+	git commit -m "independent, too" foo &&
+	test -z "$(git rev-list --left-right --cherry-pick \
+		HEAD...master -- foo)"
+'
+
 test_done