grep: fix -l/-L interaction with decoration lines

In threaded mode, git-grep emits file breaks (enabled with context, -W
and --break) into the accumulation buffers even if they are not
required.  The output collection thread then uses skip_first_line to
skip the first such line in the output, which would otherwise be at
the very top.

This is wrong when the user also specified -l/-L/-c, in which case
every line is relevant.  While arguably giving these options together
doesn't make any sense, git-grep has always quietly accepted it.  So
do not skip anything in these cases.

Signed-off-by: Albert Yale <surfingalbert@gmail.com>
Signed-off-by: Thomas Rast <trast@student.ethz.ch>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 22 insertions, 0 deletions

diff --git a/t/t7810-grep.sh b/t/t7810-grep.sh
index 7ba5b16f9..75f4716d8 100755
--- a/t/t7810-grep.sh
+++ b/t/t7810-grep.sh
@@ -246,6 +246,28 @@ do
 done
 
 cat >expected <<EOF
+file
+EOF
+test_expect_success 'grep -l -C' '
+	git grep -l -C1 foo >actual &&
+	test_cmp expected actual
+'
+
+cat >expected <<EOF
+file:5
+EOF
+test_expect_success 'grep -l -C' '
+	git grep -c -C1 foo >actual &&
+	test_cmp expected actual
+'
+
+test_expect_success 'grep -L -C' '
+	git ls-files >expected &&
+	git grep -L -C1 nonexistent_string >actual &&
+	test_cmp expected actual
+'
+
+cat >expected <<EOF
 file:foo mmap bar_mmap
 EOF