rerere.c: move error_errno() closer to the source system call

We are supposed to report errno from fopen(). fclose() between fopen()
and the report function could either change errno or reset it.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

rerere.c

@@ -489,8 +489,9 @@ static int handle_file(const char *path, unsigned char *sha1, const char *output
 	if (output) {
 		io.io.output = fopen(output, "w");
 		if (!io.io.output) {
+			error_errno("Could not write %s", output);
 			fclose(io.input);
-			return error_errno("Could not write %s", output);
+			return -1;
 		}
 	}