fix re-tagging of unittests, retag test_bigmem which completely fails now

Author: timfel

graalpython/com.oracle.graal.python.test/src/tests/test_tagged_unittests.py

@@ -44,7 +44,7 @@
 import test
 
 
-if os.environ.get("ENABLE_CPYTHON_TAGGED_UNITTESTS") == "true":
+if os.environ.get("ENABLE_CPYTHON_TAGGED_UNITTESTS") == "true" or __name__ == "__main__":
     TAGS_DIR = os.path.join(os.path.dirname(__file__), "unittest_tags")
 else:
     TAGS_DIR = "null"