Fix a few more pickle-related compatibility issues.
Review Request #10257 — Created Oct. 21, 2018 and submitted
This converts one more case of a
pickle.loads()call that had to be
converted to the
pickle_loads()compatibility function, and updates
other call sites to not prematurely convert string types when feeding in
data to load.
Unit tests pass for Python 2.7, 3.5, and 3.6.