Fix the compiler package w.r.t. the new metaclass syntax.
(It is still broken w.r.t. the new nonlocal keyword.)

Remove a series of debug prints I accidentally left in test_ast.py.
diff --git a/Lib/test/test_ast.py b/Lib/test/test_ast.py
index c702ab1..308ddae 100644
--- a/Lib/test/test_ast.py
+++ b/Lib/test/test_ast.py
@@ -144,13 +144,9 @@
                                 (eval_tests, eval_results, "eval")):
         for i, o in itertools.izip(input, output):
             ast_tree = compile(i, "?", kind, 0x400)
-            if to_tuple(ast_tree) != o:
-                print("i=", i)
-                print("o=", o)
-                print("kind=", kind)
-                print("tree=", ast_tree)
-                print("tuple=", to_tuple(ast_tree))
-            assert to_tuple(ast_tree) == o
+            tup = to_tuple(ast_tree)
+            assert tup == o, ("kind=%r\ninput=%r\nexpected=%r\ngot=%r" %
+                              (kind, i, o, tup))
             test_order(ast_tree, (0, 0))
 
 #### EVERYTHING BELOW IS GENERATED #####
diff --git a/Lib/test/test_compiler.py b/Lib/test/test_compiler.py
index 8535f42..4fb6cc1 100644
--- a/Lib/test/test_compiler.py
+++ b/Lib/test/test_compiler.py
@@ -50,8 +50,8 @@
                     try:
                         compiler.compile(buf, basename, "exec")
                     except Exception as e:
-                        args = list(e.args)
-                        args[0] += "[in file %s]" % basename
+                        args = list(e.args) or [""]
+                        args[0] = "%s [in file %s]" % (args[0], basename)
                         e.args = tuple(args)
                         raise