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_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