Try a different way of detecting buildbot.

Author: jaraco

Lib/test/test_importlib/metadata/_issue132947.py

@@ -8,7 +8,8 @@ def skip_on_buildbot(func):
     changes, only on some buildbot runners, the tests will fail with
     ResourceWarnings.
     """
-    is_buildbot = 'BUILDBOT_RUN' in os.environ or 'BUILDBOT' in os.environ
+    is_buildbot = any(key.startswith('BUILDBOT') for key in os.environ)
+    assert is_buildbot, f'no buildbot in {list(os.environ)}'
     skipper = unittest.skip("Causes Resource Warnings (python/cpython#132947)")
     wrapper = skipper if is_buildbot else lambda x: x
     return wrapper(func)