builtin/revert.c: don't dereference a NULL pointer
cherry-pick will segfault when transplanting a root commit if the --ff
option is used. This happens because the "parent" pointer is set to NULL
when the commit being cherry-picked has no parents. Later, when "parent"
is dereferenced, the cherry-pick segfaults.
Fix this by checking whether "parent" is NULL before dereferencing it and
add a test for this case of cherry-picking a root commit with --ff.
Reported-by: Zbyszek Szmek <zbyszek@in.waw.pl>
Signed-off-by: Brandon Casey <casey@nrlssc.navy.mil>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/t/t3506-cherry-pick-ff.sh b/t/t3506-cherry-pick-ff.sh
index e17ae71..51ca391 100755
--- a/t/t3506-cherry-pick-ff.sh
+++ b/t/t3506-cherry-pick-ff.sh
@@ -95,4 +95,14 @@
test_must_fail git cherry-pick --ff -m 3 C
'
+test_expect_success 'cherry pick a root commit with --ff' '
+ git reset --hard first -- &&
+ git rm file1 &&
+ echo first >file2 &&
+ git add file2 &&
+ git commit --amend -m "file2" &&
+ git cherry-pick --ff first &&
+ test "$(git rev-parse --verify HEAD)" = "1df192cd8bc58a2b275d842cede4d221ad9000d1"
+'
+
test_done
