Windows' gevent is always special!

src/python/grpcio_tests/commands.py

@@ -191,9 +191,7 @@ class TestGevent(setuptools.Command):
     )
     BANNED_WINDOWS_TESTS = (
         # TODO(https://github.com/grpc/grpc/pull/15411) enable this test
-        'unit._dns_resolver_test.DNSResolverTest.test_connect_loopback',
-        'unit._channel_close_test.ChannelCloseTest',
-    )
+        'unit._dns_resolver_test.DNSResolverTest.test_connect_loopback',)
     description = 'run tests with gevent.  Assumes grpc/gevent are installed'
     user_options = []
 

tools/run_tests/helper_scripts/build_python.sh

@@ -166,7 +166,7 @@ pip_install_dir() {
 }
 
 case "$VENV" in
-  *py35_gevent*)
+  *py36_gevent*)
   # TODO(https://github.com/grpc/grpc/issues/15411) unpin this
   $VENV_PYTHON -m pip install gevent==1.3.b1
   ;;