On wrestling with beam/issues/21104

[Pablo Estrada via dev <de...@beam.apache.org>]

Hi all,
I've spent a few days trying to narrow down whatever is going on with
https://github.com/apache/beam/issues/21104.

The bug reproduces frequently on Jenkins and very rarely on my laptop
(sometimes ~20 min, sometimes hours, sometimes I give up after it doesn't
reproduce all night).

Seeing as how it reproduces so frequently in our Jenkins env (see:
https://ci-beam.apache.org/job/beam_PreCommit_Python_Cron/), I would like
to do the following:

1. Add debug information to log as much context as possible when it occurs
2. Create a bug blocking the next release to revert the change
3. Revert before the next release

And hopefully this experiment will let us gather more information about the
bug.

Is everyone in favor of this? Is anyone against? Comments?
Thanks!
-P.