notify: just use email.errors email.Errors is a proxy object to email.errors on Python 2.

rust-chg: add struct holding information needed to spawn server process The Locator will handle the initialization of the connection. It will spawn server processes as needed.

rust-chg: install logger if $CHGDEBUG is set This is modeled after the example logger and debugmsg() of chg/util.c. https://docs.rs/log/0.4.5/log/#implementing-a-logger

rust-chg: depend on log and tokio_timer I'll start porting the daemon management functions from chg of C, which will be difficult to debug without some logging facility. AFAIK, the log crate is easy-to-use and widely used. tokio_timer provides sleep() helper to be used while spawning a server process.

rust-chg: suppress panic while writing chg error to stderr Otherwise "chg >/dev/full 2>&1" would exit with 101. Spotted by test-basic.t.

logcmdutil: add a helpful assertion to catch mistyped templates early This would have made a defect in test-notify.t much easier to figure out. Differential Revision: https://phab.mercurial-scm.org/D5097

notify: adapt to new location of email module's errors Differential Revision: https://phab.mercurial-scm.org/D5099

notify: add some b prefixes # skip-blame just b prefixes Differential Revision: https://phab.mercurial-scm.org/D5098

py3: fix test-diff-color.t Differential Revision: https://phab.mercurial-scm.org/D5095

py3: fix test-revlog.t The mpatchError has a trailing comma on Python 2 but not on Python 3, so use a glob to handle both Python 2 and Python 3. Differential Revision: https://phab.mercurial-scm.org/D5093