---
fixes:
  - |
    In some multithreading situations the mocker might try and replace an
    already patched object from a different thread. To make this thread safe we
    will put a lock around the mocker so that only one thread can work with the
    mocker at any time. This has to be a reentrant lock as the same thread can
    go through it multiple times.

Add a release note for the RLock
Add a release note for the RLock

We should document this in release notes for the release as if there is
a problem with the release it's most likely to come from this.
