phases: do not exchange secret changesets
Any secret changesets will be excluded from pull and push. Phase data are
properly synchronized on pull and push if a changeset is seen as secret locally
but is non-secret remote side.
This patch does not handle the case of a changeset secret on remote but known
locally.
To run the tests, do:
cd tests/
python run-tests.py
See http://mercurial.selenic.com/wiki/WritingTests for
more information on writing tests.