Merge branch 'jk/empty-pick-fix'

Handling of an empty range by "git cherry-pick" was inconsistent
depending on how the range ended up to be empty, which has been
corrected.

* jk/empty-pick-fix:
  sequencer: don't say BUG on bogus input
  sequencer: handle empty-set cases consistently

Author: gitster

sequencer.c

@@ -1864,8 +1864,6 @@ static int prepare_revs(struct replay_opts *opts)
 	if (prepare_revision_walk(opts->revs))
 		return error(_("revision walk setup failed"));
 
-	if (!opts->revs->commits)
-		return error(_("empty commit set passed"));
 	return 0;
 }
 
@@ -2323,6 +2321,10 @@ static int walk_revs_populate_todo(struct todo_list *todo_list,
 			short_commit_name(commit), subject_len, subject);
 		unuse_commit_buffer(commit, commit_buffer);
 	}
+
+	if (!todo_list->nr)
+		return error(_("empty commit set passed"));
+
 	return 0;
 }
 
@@ -3658,8 +3660,10 @@ int sequencer_pick_revisions(struct replay_opts *opts)
 		if (prepare_revision_walk(opts->revs))
 			return error(_("revision walk setup failed"));
 		cmit = get_revision(opts->revs);
-		if (!cmit || get_revision(opts->revs))
-			return error("BUG: expected exactly one commit from walk");
+		if (!cmit)
+			return error(_("empty commit set passed"));
+		if (get_revision(opts->revs))
+			BUG("unexpected extra commit from walk");
 		return single_pick(cmit, opts);
 	}
 

t/t3510-cherry-pick-sequence.sh

@@ -480,11 +480,16 @@ test_expect_success 'malformed instruction sheet 2' '
 	test_expect_code 128 git cherry-pick --continue
 '
 
-test_expect_success 'empty commit set' '
+test_expect_success 'empty commit set (no commits to walk)' '
 	pristine_detach initial &&
 	test_expect_code 128 git cherry-pick base..base
 '
 
+test_expect_success 'empty commit set (culled during walk)' '
+	pristine_detach initial &&
+	test_expect_code 128 git cherry-pick -2 --author=no.such.author base
+'
+
 test_expect_success 'malformed instruction sheet 3' '
 	pristine_detach initial &&
 	test_expect_code 1 git cherry-pick base..anotherpick &&