launch_editor(): read the file, even when EDITOR=:

Earlier we just returned in case EDITOR=: but the message stored
in the file was not read back.  Fix this, at the same time
simplifying the code as suggested by Johannes Sixt.

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

builtin-tag.c

@@ -20,8 +20,6 @@ static char signingkey[1000];
 void launch_editor(const char *path, struct strbuf *buffer)
 {
 	const char *editor, *terminal;
-	struct child_process child;
-	const char *args[3];
 
 	editor = getenv("GIT_EDITOR");
 	if (!editor && editor_program)
@@ -42,17 +40,12 @@ void launch_editor(const char *path, struct strbuf *buffer)
 	if (!editor)
 		editor = "vi";
 
-	if (!strcmp(editor, ":"))
-		return;
-
-	memset(&child, 0, sizeof(child));
-	child.argv = args;
-	args[0] = editor;
-	args[1] = path;
-	args[2] = NULL;
+	if (strcmp(editor, ":")) {
+		const char *args[] = { editor, path, NULL };
 
-	if (run_command(&child))
-		die("There was a problem with the editor %s.", editor);
+		if (run_command_v_opt(args, 0))
+			die("There was a problem with the editor %s.", editor);
+	}
 
 	if (strbuf_read_file(buffer, path, 0) < 0)
 		die("could not read message file '%s': %s",