t7003: add test to filter a branch with a commit at epoch

Running filter-branch on a history that has a commit with timestamp
at epoch used to fail, but it should have been fixed.  Add test to
make sure it won't break again.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

2 files changed, 13 insertions, 3 deletions

diff --git a/t/t7003-filter-branch.sh b/t/t7003-filter-branch.sh
index e0227730de..4d13e10de1 100755
--- a/t/t7003-filter-branch.sh
+++ b/t/t7003-filter-branch.sh
@@ -5,7 +5,8 @@ test_description='git filter-branch'
 
 test_expect_success 'setup' '
 	test_commit A &&
-	test_commit B &&
+	GIT_COMMITTER_DATE="@0 +0000" GIT_AUTHOR_DATE="@0 +0000" &&
+	test_commit --notick B &&
 	git checkout -b branch B &&
 	test_commit D &&
 	mkdir dir &&
diff --git a/t/test-lib.sh b/t/test-lib.sh
index d7dfc8b0b1..f3a50d4cb3 100644
--- a/t/test-lib.sh
+++ b/t/test-lib.sh
@@ -335,10 +335,19 @@ test_tick () {
 # Both <file> and <contents> default to <message>.
 
 test_commit () {
-	file=${2:-"$1.t"}
+	notick= &&
+	if test "z$1" = "z--notick"
+	then
+		notick=yes
+		shift
+	fi &&
+	file=${2:-"$1.t"} &&
 	echo "${3-$1}" > "$file" &&
 	git add "$file" &&
-	test_tick &&
+	if test -z "$notick"
+	then
+		test_tick
+	fi &&
 	git commit -m "$1" &&
 	git tag "$1"
 }