v1.7.2

Bug Fixes

• always use brute-force counting with Datastore emulator and clean up related hacks (#585) (8480a8b)
• return a tuple when empty result returned on query (#582) (7cf0e87)
• support empty not_finished messages that cause query.count() to return early (#580) (fc31553), closes #575

Documentation

• Add urlsafe() info to migration notes (#579) (9df2f9f)