[PATCH 2/2] Avoid a segmentation fault with renaming merges

[Johannes Schindelin <johannes.schindelin@gmx.de>]

Under very particular circumstances, merge-recursive's `add_cacheinfo()`
function gets a `NULL` returned from `refresh_cache_entry()` without
expecting it, and subsequently passes it to `add_cache_entry()` which
consequently crashes.

Let's not crash.

This fixes https://github.com/git-for-windows/git/issues/952

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
 merge-recursive.c             | 2 ++
 t/t3501-revert-cherry-pick.sh | 2 +-
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/merge-recursive.c b/merge-recursive.c
index 9041c2f149..609061f58a 100644
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -235,6 +235,8 @@ static int add_cacheinfo(struct merge_options *o,
 		struct cache_entry *nce;
 
 		nce = refresh_cache_entry(ce, CE_MATCH_REFRESH | CE_MATCH_IGNORE_MISSING);
+		if (!nce)
+			return err(o, _("addinfo: '%s' is not up-to-date"), path);
 		if (nce != ce)
 			ret = add_cache_entry(nce, options);
 	}
diff --git a/t/t3501-revert-cherry-pick.sh b/t/t3501-revert-cherry-pick.sh
index d96d391af3..8e21840f11 100755
--- a/t/t3501-revert-cherry-pick.sh
+++ b/t/t3501-revert-cherry-pick.sh
@@ -141,7 +141,7 @@ test_expect_success 'cherry-pick "-" works with arguments' '
 	test_cmp expect actual
 '
 
-test_expect_failure 'cherry-pick fails gracefully with dirty renamed file' '
+test_expect_success 'cherry-pick fails gracefully with dirty renamed file' '
 	test_commit to-rename &&
 	git checkout -b unrelated &&
 	test_commit unrelated &&
-- 
2.11.0.rc3.windows.1