tests: make one of 'worker process exited' line option in test-chg.t I investigated and it seems like under high load, the child process is already there and no new fork was created. Hence the process was not closed.

infinitepush: fix `{get,put}_args` formatting on Python 3 Calling `.format()` on a byte-string does not work, thus causing an exception on Python 3. This commit adds a function to paper over the difference. Differential Revision: https://phab.mercurial-scm.org/D8781