zeroconf: notify the Zeroconf threads when hg exits Zeroconf launches two threads in the background, and they wait on Condition objects to exit. We need to call Zeroconf.close() to release those conditions so that threads can gracefully exit. This means that an interrupt on the hg process will now gracefully propagate to the Zeroconf children, fixing that bug which did not allow us to kill an `hg serve` process.

color: use ui.formatted() to test TTYness, not sys.stdout.isatty() This fixes the color extension not working with pager (broken in 877390020477). The pager extension already sets ui.formatted=True to allow this use case.

pushkey: add hooks for pushkey/listkeys

test-patchbomb.t: clean up progress tests

util: really drop size from readfile

util: add readfile() & writefile() helper functions These two functions allow quickly reading or writing a file, without relying on reference counting to close the file handle afterwards.

revset aliases

opener: add read & write utility methods The two new methods are useful for quickly opening a file for reading or writing. Unlike 'opener(...).read()', they ensure they the file is immediately closed without relying on CPython reference counting.