editor: use run_command's shell feature

Now that run_command implements the same code in a more
general form, we can make use of it.

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

editor.c

@@ -36,26 +36,9 @@ int launch_editor(const char *path, struct strbuf *buffer, const char *const *en
 		return error("Terminal is dumb, but EDITOR unset");
 
 	if (strcmp(editor, ":")) {
-		size_t len = strlen(editor);
-		int i = 0;
-		int failed;
-		const char *args[6];
-		struct strbuf arg0 = STRBUF_INIT;
+		const char *args[] = { editor, path, NULL };
 
-		if (strcspn(editor, "|&;<>()$`\\\"' \t\n*?[#~=%") != len) {
-			/* there are specials */
-			strbuf_addf(&arg0, "%s \"$@\"", editor);
-			args[i++] = "sh";
-			args[i++] = "-c";
-			args[i++] = arg0.buf;
-		}
-		args[i++] = editor;
-		args[i++] = path;
-		args[i] = NULL;
-
-		failed = run_command_v_opt_cd_env(args, 0, NULL, env);
-		strbuf_release(&arg0);
-		if (failed)
+		if (run_command_v_opt_cd_env(args, RUN_USING_SHELL, NULL, env))
 			return error("There was a problem with the editor '%s'.",
 					editor);
 	}