chgserver: change random state after fork
Before this patch, extensions expecting a different random state per command
will break since the chg request handler will inherit a same random state
from the parent daemon process.
This patch addresses the issue by calling random.seed() after fork.
To run the tests, do:
cd tests/
python run-tests.py
See https://mercurial-scm.org/wiki/WritingTests for
more information on writing tests.