run_external_diff: hoist common bits out of conditional

Whether we have diff_filespecs to give to the diff command
or not, we always are going to run the program and pass it
the pathname. Let's pull that duplicated part out of the
conditional to make it more obvious.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff.c

@@ -2911,13 +2911,14 @@ static void run_external_diff(const char *pgm,
 	struct argv_array env = ARGV_ARRAY_INIT;
 	struct diff_queue_struct *q = &diff_queued_diff;
 
+	argv_array_push(&argv, pgm);
+	argv_array_push(&argv, name);
+
 	if (one && two) {
 		struct diff_tempfile *temp_one, *temp_two;
 		const char *othername = (other ? other : name);
 		temp_one = prepare_temp_file(name, one);
 		temp_two = prepare_temp_file(othername, two);
-		argv_array_push(&argv, pgm);
-		argv_array_push(&argv, name);
 		argv_array_push(&argv, temp_one->name);
 		argv_array_push(&argv, temp_one->hex);
 		argv_array_push(&argv, temp_one->mode);
@@ -2928,9 +2929,6 @@ static void run_external_diff(const char *pgm,
 			argv_array_push(&argv, other);
 			argv_array_push(&argv, xfrm_msg);
 		}
-	} else {
-		argv_array_push(&argv, pgm);
-		argv_array_push(&argv, name);
 	}
 
 	argv_array_pushf(&env, "GIT_DIFF_PATH_COUNTER=%d", ++o->diff_path_counter);