revision: fix --left/right-only use with unrelated histories

This is a similar fix as 023756f (revision walker: --cherry-pick is a
limited operation), but for the --left-only and --right-only options.

When computing a symmetric difference between two unrelated histories,
no suitable merge base exists, and so no boundary commit is flagged as
UNINTERESTING.  Previously, we relied on the presence of such boundary
to trigger limiting and thus consideration of either "revs->left_only"
or "revs->right_only".

A number of other entries in the option parser have started including
overrides for "revs->limited = 1".  Do the same for these options.

Signed-off-by: Matt Hunter <m@lfurio.us>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: trmalfurious

revision.c

@@ -2488,10 +2488,12 @@ static int handle_revision_opt(struct rev_info *revs, int argc, const char **arg
 			die(_("options '%s' and '%s' cannot be used together"),
 			    "--left-only", "--right-only/--cherry");
 		revs->left_only = 1;
+		revs->limited = 1;
 	} else if (!strcmp(arg, "--right-only")) {
 		if (revs->left_only)
 			die(_("options '%s' and '%s' cannot be used together"), "--right-only", "--left-only");
 		revs->right_only = 1;
+		revs->limited = 1;
 	} else if (!strcmp(arg, "--cherry")) {
 		if (revs->left_only)
 			die(_("options '%s' and '%s' cannot be used together"), "--cherry", "--left-only");

t/t6000-rev-list-misc.sh

@@ -182,4 +182,19 @@ test_expect_success 'rev-list --unpacked' '
 	test_cmp expect actual
 '
 
+test_expect_success 'rev-list one-sided unrelated symmetric diff' '
+	test_tick &&
+	git commit --allow-empty -m xyz &&
+	git branch cmp &&
+	git rebase --force-rebase --root &&
+
+	git rev-list --left-only  HEAD...cmp >head &&
+	git rev-list --right-only HEAD...cmp >cmp  &&
+
+	sort head >head.sorted &&
+	sort cmp >cmp.sorted &&
+	comm -12 head.sorted cmp.sorted >actual &&
+	test_line_count = 0 actual
+'
+
 test_done