Get the tests passing again

tools/python/defs.bzl

@@ -166,7 +166,8 @@ def py_project(name=None,
                lib_data=None,
                test_srcs=None,
                test_deps=None,
-               test_data=None):
+               test_data=None,
+               test_tags=[]):
     """
     A helper for defining conventionally-formatted python project.
 
@@ -259,4 +260,5 @@ def py_project(name=None,
                     "test/python",
                     "test/resources",
                 ],
+                tags=test_tags,
             )