send-pack: segfault fix on forced push

When pushing to overwrite a ref that points at a commit we do
not even have, the recent "terse push" patch tried to get a
unique abbreviation for the non-existent (from our point of
view) object, which resulted in strcpy(buf, NULL) and
segfaulted.

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

1 files changed, 42 insertions, 0 deletions

diff --git a/t/t5405-send-pack-rewind.sh b/t/t5405-send-pack-rewind.sh
new file mode 100755
index 0000000000..86abc62271
--- /dev/null
+++ b/t/t5405-send-pack-rewind.sh
@@ -0,0 +1,42 @@
+#!/bin/sh
+
+test_description='forced push to replace commit we do not have'
+
+. ./test-lib.sh
+
+test_expect_success setup '
+
+	>file1 && git add file1 && test_tick &&
+	git commit -m Initial &&
+
+	mkdir another && (
+		cd another &&
+		git init &&
+		git fetch .. master:master
+	) &&
+
+	>file2 && git add file2 && test_tick &&
+	git commit -m Second
+
+'
+
+test_expect_success 'non forced push should die not segfault' '
+
+	(
+		cd another &&
+		git push .. master:master
+		test $? = 1
+	)
+
+'
+
+test_expect_success 'forced push should succeed' '
+
+	(
+		cd another &&
+		git push .. +master:master
+	)
+
+'
+
+test_done