This one is very interesting to me because the code from the mighty gevent-zeromq library which brought gevent support to pyzmq has been merged into it ! I find it very humble and positive for the Open Source community to see such merges and want to express my gratitude to Travis Cline and the zeroMQ team for that.
Migrating is as easy as :
# gevent-zeromq previous way from gevent_zeromq import zmq # pyzmq new way from pyzmq.green import zmq
I strongly encourage you to read the changelog.
Bugfix release, the main point is that PyMongo will no longer select a replica set member for read operations that is not in primary or secondary state. Here is the changelog.