Fix collective retry logic
Fix collective retry logic

It erroneously treated a thread as a bool, need
to check if None to know if it is scheduled.

jjohnson42/confluent,xcat2/confluent,xcat2/confluent,xcat2/confluent,xcat2/confluent,jjohnson42/confluent,jjohnson42/confluent,xcat2/confluent,jjohnson42/confluent,jjohnson42/confluent