Message11494

Thanks for investigating this so carefully.

You write "The bug is obviously due to regexp object shared somewhere between threads", I suppose because in your example it's the only object that obviously is shared between threads. A couple of things puzzle me:
1. Very little here has changed since 2.7.1b3 (Feb 2016).
2. The only obviously shared object (REGEX) appears not to be mutated. 

Which causes me to wonder whether there might be a fundamental problem where module-global objects might be inconsistent between threads. Others may have more insight.