If unkown version of Ceph is used, assert exception is raised

[Evgeniy L]

If there is unknown Ceph release is used, UnkownCephRelease exception should be used instead of gneral Assert exception, so on higher level it's possible to handle specifically this error, without catching all assert exceptions.

https://review.openstack.org/#/c/204814/21/nailgun/nailgun/utils/ceph.py

[Alexander Kislitsky (akislitsky)]

Also get_pool_pg_count can be refactored to set of small functions. It could improve code readability and tests coverage.

[Kostiantyn Danylov (kdanylov)]

Whole this ticket is a nice example of WAT.
View, please, https://www.youtube.com/watch?v=o9pEzgHorH0.
There absolutely no reason for new exception class. AssertionError mean, that something really bad with
internal logic. It should be logged and converted into 5XX code

[Dmitry Pyzhov (dpyzhov)]

We passed SCF in 8.0. Moving the bug to 9.0.