Comment 2 for bug 1862315

Looking at ReaderWriterLock from fasteners lib, read_lock() function (which is eventually used by dhcp agent):
https://github.com/harlowja/fasteners/blob/0.15/fasteners/lock.py#L160-L202

the func is supposed to "wait until no active or pending writers", but from code it looks it only checks that current thread is not in pending writers and doesn't actually check that there are no other pending writers. I might be missing something, so going to contact @harlowja.