The commit I168fffac8002f274a905cfd53ac4f6c9abe18803 added a wrapper
around fasteners.ReaderWriterLock to fix up an issue with eventlet. But
the wrapper was added to nova.utils module that is use not only by the
nova tests but also the nova production code. This made the fixture
library a dependency of the nova production code. While the current
ReaderWriterLock usage only limited to the nova test sub tree. The
I712f88fc1b6053fe6d1f13e708f3bd8874452a8f commit fix the issue of not
having fixtures in the nova requirements.txt. However I think a better
fix is to move the wrapper to the test subtree instead. This patch does
that and restores the state of the requirements.txt
Change-Id: I6903ce53b9b91325f7268cf2ebd02e4488579560
Related-Bug: #1958075
a341851f15