The changes were mostly in the Persistent module. Here, the changes were minimal:

- Introduce zodbpickle for PyPy and Python 2.7 to fix noload.

- Centralize the construction of Picklers/Unpicklers to account for the differences between Python2/3/zodbpickle.

- A few extra gc.collect() calls.

- Some minor printing differences in the doctests due to the Python implementation of BTrees.