discovery: prevent crash caused by prune marker having no parent data If a marker has no parent information, parents field is set to None, which caused TypeError. I think this shouldn't normally happen, but somehow I have such marker in my repo.

color: point to the global help in the example hgrc This is probably the best way to have users learn more is they need too.

color: reflect the new default in the example hgrc Color is enabled by default so un-commenting the line would not have any effect. We'll point to the help in the next changeset.

color: point to the config help in global help topic We point out at the help of the config option for user who wants to learn more about the possible config value. The suggested command returns some other extra (color related) results, but this is bug to fix outside of the freeze.

color: reflect the new default in global help topic We point out that color is enabled by default.

docs: describe ui.color consistently with --color The --color option is described to accept "boolean, always, auto, never, or debug". Let's use a similar description for ui.color. Also fix the formatting to use double quotes as we seem to use for about half the values in config.txt (the other half uses double backticks). Also use uppercase Boolean for consistency within the file.

test: glob out variation from 'HGPORT' length On system where HGTEST_PORT is configured to a value an order a magnitude lower or higher than the default. The number of digit in the HGPORT changes and this test breaks.

lock: avoid unintentional lock acquisition at failure of readlock Acquiring lock by vfs.makelock() and getting lock holder (aka "locker") information by vfs.readlock() aren't atomic action. Therefore, failure of the former doesn't ensure success of the latter. Before this patch, lock is unintentionally acquired, if ENOENT causes failure of vfs.readlock() while 5 times retrying, because lock._trylock() returns to caller silently after retrying, and lock.lock() assumes that lock._trylock() returns successfully only if lock is acquired. In this case, lock symlink (or file) isn't created, even though lock is treated as acquired in memory. To avoid this issue, this patch makes lock._trylock() raise LockHeld(EAGAIN) at the end of it, if lock isn't acquired while retrying. An empty "locker" meaning "busy for frequent lock/unlock by many processes" might appear in an abortion message, if lock acquisition fails. Therefore, this patch also does: - use '%r' to increase visibility of "locker", even if it is empty - show hint message to explain what empty "locker" means