state: don't have a dict like interface for cmdstate class
This patch changes the cmdstate class to stop having a dict like interface and
delete the __nonzero__ function. After this patch, the save fuction takes a dict
to store the data and read function returns a dict of the data stored.
Differential Revision: https://phab.mercurial-scm.org/D3572
To run the tests, do:
cd tests/
python run-tests.py
See https://mercurial-scm.org/wiki/WritingTests for
more information on writing tests.