merge-recursive: handle NULL in add_cacheinfo() correctly

1335d76e45 ("merge: avoid "safer crlf" during recording of merge
results", 2016-07-08) tried to split make_cache_entry() call made
with CE_MATCH_REFRESH into a call to make_cache_entry() without one,
followed by a call to add_cache_entry(), refresh_cache() and another
add_cache_entry() as needed.  However the conversion was botched in
that it forgot that refresh_cache() can return NULL, which was
handled correctly in make_cache_entry() but in the updated code.

This fixes git-for-windows/git#952

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
(cherry picked from commit 55e9f0e5c9a918c246b7eae1fe2a2e954f6426af)
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>

Gbp-Pq: Name merge-recursive-handle-NULL-in-add_cacheinfo-correctl.diff

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 error(_("addinfo_cache failed for path '%s'"), path);
 		if (nce != ce)
 			ret = add_cache_entry(nce, options);
 	}

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 works with dirty renamed file' '
+test_expect_success 'cherry-pick works with dirty renamed file' '
 	test_commit to-rename &&
 	git checkout -b unrelated &&
 	test_commit unrelated &&