…ython#462)

* bpo-28087: Skip test_asyncore and test_eintr poll failures on macOS

Skip some tests of select.poll when running on macOS due to unresolved
issues with the underlying system poll function on some macOS versions.

(cherry picked from commit de04644)

…acOS (#463) (#1424)

Skip some tests of select.poll when running on macOS due to unresolved
issues with the underlying system poll function on some macOS versions.

(cherry picked from commit de04644)
(cherry picked from commit 1d391f9)

We upgraded the redis environment on Heroku a couple days ago. In the new environment, the REDIS_URL environment variable was changed to HEROKU_REDIS_MAROON_TLS_URL.
Updated the code where we were hardcoding it to the old to url.

Fixes #462