I can't reproduce this on the latest devstack:
$ keystone-manage db_sync CRITICAL keystone [-] Unhandled error: NoSuchModuleError: Can't load plugin: sqlalchemy.dialects:mysql.pymsql
I turned debug logging off but didn't change any other logging configuration for devstack. Do you have any other information about your deployment that would help reproduce this?
I can't reproduce this on the latest devstack:
$ keystone-manage db_sync dialects: mysql.pymsql
CRITICAL keystone [-] Unhandled error: NoSuchModuleError: Can't load plugin: sqlalchemy.
I turned debug logging off but didn't change any other logging configuration for devstack. Do you have any other information about your deployment that would help reproduce this?