py3-gevent-1.4.0 incompatible with python 3.8
I recently came across a bug similar to this one: https://github.com/gevent/gevent/issues/1491
Reading the comments, it looks like gevent 1.4.0 is more or less incompatible with python 3.8. Unfortunately, those are the two versions currently in alpine 3.11. I would therefore suggest upgrading gevent to version 1.5.0 which was release about 2 weeks ago.