apply: test rename 2 to 1

Test that we can apply a patch that renames two different files to the
same target filename.  Git itself handles this scenario in a last-write
wins, such that the rename listed last is the one persisted in the
target.  Ensure that we do the same.

tests/apply/apply_helpers.h

@@ -235,6 +235,16 @@
 	"rename from beef.txt\n" \
 	"rename to asparagus.txt\n"
 
+#define DIFF_RENAME_2_TO_1 \
+	"diff --git a/asparagus.txt b/2.txt\n" \
+	"similarity index 100%\n" \
+	"rename from asparagus.txt\n" \
+	"rename to 2.txt\n" \
+	"diff --git a/beef.txt b/2.txt\n" \
+	"similarity index 100%\n" \
+	"rename from beef.txt\n" \
+	"rename to 2.txt\n"
+
 struct iterator_compare_data {
 	struct merge_index_entry *expected;
 	size_t cnt;

tests/apply/both.c

@@ -524,3 +524,27 @@ void test_apply_both__rename_circular(void)
 
 	git_diff_free(diff);
 }
+
+void test_apply_both__rename_2_to_1(void)
+{
+	git_diff *diff;
+
+	struct merge_index_entry both_expected[] = {
+		{ 0100644, "68f6182f4c85d39e1309d97c7e456156dc9c0096", 0, "2.txt" },
+		{ 0100644, "4b7c5650008b2e747fe1809eeb5a1dde0e80850a", 0, "bouilli.txt" },
+		{ 0100644, "c4e6cca3ec6ae0148ed231f97257df8c311e015f", 0, "gravy.txt" },
+		{ 0100644, "68af1fc7407fd9addf1701a87eb1c95c7494c598", 0, "oyster.txt" },
+		{ 0100644, "94d2c01087f48213bd157222d54edfefd77c9bba", 0, "veal.txt" }
+	};
+	size_t both_expected_cnt = sizeof(both_expected) /
+		sizeof(struct merge_index_entry);
+
+	cl_git_pass(git_diff_from_buffer(&diff, DIFF_RENAME_2_TO_1,
+		strlen(DIFF_RENAME_2_TO_1)));
+	cl_git_pass(git_apply(repo, diff, GIT_APPLY_LOCATION_BOTH, NULL));
+
+	validate_apply_index(repo, both_expected, both_expected_cnt);
+	validate_apply_workdir(repo, both_expected, both_expected_cnt);
+
+	git_diff_free(diff);
+}