Rewrite without using try-except to break out of two loops.

Lib/test/test_nis.py

@@ -5,7 +5,7 @@ if __name__ == '__main__':
     verbose = 1
 
 maps = nis.maps()
-try:
+done = 0
 for nismap in maps:
     if verbose:
 	print nismap
@@ -20,6 +20,7 @@ try:
 	else:
 	    # just test the one key, otherwise this test could take a
 	    # very long time
-		raise 'done'
-except 'done':
-    pass
+	    done = 1
+	    break
+    if done:
+	break