git_config_rename_section_in_file(): avoid resource leak

In case of errors, we really want the file descriptor to be closed.

Discovered by a Coverity scan.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

config.c

@@ -2621,7 +2621,7 @@ int git_config_rename_section_in_file(const char *config_filename,
 	struct lock_file *lock;
 	int out_fd;
 	char buf[1024];
-	FILE *config_file;
+	FILE *config_file = NULL;
 	struct stat st;
 
 	if (new_name && !section_name_is_ok(new_name)) {
@@ -2703,11 +2703,14 @@ int git_config_rename_section_in_file(const char *config_filename,
 		}
 	}
 	fclose(config_file);
+	config_file = NULL;
 commit_and_out:
 	if (commit_lock_file(lock) < 0)
 		ret = error_errno("could not write config file %s",
 				  config_filename);
 out:
+	if (config_file)
+		fclose(config_file);
 	rollback_lock_file(lock);
 out_no_rollback:
 	free(filename_buf);