script: Initialize isterm and shell earlier in main()

index 14a44e1..ed8e83d 100644
@@ -236,6 +236,12 @@ main(int argc, char **argv) {
 	argc -= optind;
 	argv += optind;
 
+	shell = getenv("SHELL");
+	if (shell == NULL)
+		shell = _PATH_BSHELL;
+
+	isterm = isatty(STDIN_FILENO);
+
 	if (argc > 0)
 		fname = argv[0];
 	else {

@@ -248,10 +254,6 @@ main(int argc, char **argv) {
 		fail();
 	}
 
-	shell = getenv("SHELL");
-	if (shell == NULL)
-		shell = _PATH_BSHELL;
-
 	getmaster();
 	if (!qflg)
 		printf(_("Script started, file is %s\n"), fname);

@@ -635,8 +637,6 @@ getmaster(void) {
 #if defined(HAVE_LIBUTIL) && defined(HAVE_PTY_H)
 	int rc;
 
-	isterm = isatty(STDIN_FILENO);
-
 	if (isterm) {
 		if (tcgetattr(STDIN_FILENO, &tt) != 0)
 			err(EXIT_FAILURE, _("failed to get terminal attributes"));