Merge pull request #2622 from libgit2/refresh-config-snapshot

Refresh git configuration before looking for the tracking branch redux.

src/config_file.c

@@ -767,12 +767,17 @@ static int config_readonly_open(git_config_backend *cfg, git_config_level_t leve
 {
 	diskfile_readonly_backend *b = (diskfile_readonly_backend *) cfg;
 	diskfile_backend *src = b->snapshot_from;
+	diskfile_header *src_header = &src->header;
 	refcounted_strmap *src_map;
+	int error;
+
+	if (!src_header->readonly && (error = config_refresh(&src_header->parent)) < 0)
+		return error;
 
 	/* We're just copying data, don't care about the level */
 	GIT_UNUSED(level);
 
-	src_map = refcounted_strmap_take(&src->header);
+	src_map = refcounted_strmap_take(src_header);
 	b->header.values = src_map;
 
 	return 0;

tests/config/snapshot.c

@@ -3,7 +3,7 @@
 void test_config_snapshot__create_snapshot(void)
 {
 	int32_t tmp;
-	git_config *cfg, *snapshot;
+	git_config *cfg, *snapshot, *new_snapshot;
 	const char *filename = "config-ext-change";
 
 	cl_git_mkfile(filename, "[old]\nvalue = 5\n");
@@ -24,6 +24,19 @@ void test_config_snapshot__create_snapshot(void)
 	cl_git_pass(git_config_get_int32(&tmp, snapshot, "old.value"));
 	cl_assert_equal_i(5, tmp);
 
+	/* Change the value on the file itself (simulate external process) */
+	cl_git_mkfile(filename, "[old]\nvalue = 999\n");
+
+	cl_git_pass(git_config_snapshot(&new_snapshot, cfg));
+
+	/* New snapshot should see new value */
+	cl_git_pass(git_config_get_int32(&tmp, new_snapshot, "old.value"));
+	cl_assert_equal_i(999, tmp);
+
+	/* Old snapshot should still have the old value */
+	cl_git_pass(git_config_get_int32(&tmp, snapshot, "old.value"));
+	cl_assert_equal_i(5, tmp);
+	
 	git_config_free(snapshot);
 	git_config_free(cfg);
 }