shelve: check the actual shelvestate in morestatus
The rebasestate is a lower level implementation details that we are trying to
remove.
Differential Revision: https://phab.mercurial-scm.org/D3687
To run the tests, do:
cd tests/
python run-tests.py
See https://mercurial-scm.org/wiki/WritingTests for
more information on writing tests.