lock: include Linux pid namespace identifier in prefix Previously, the lock only contains a hostname as an attempt to detect pid namespace difference. However, that's not enough on modern Linux - a single hostname could have different pid namespaces. That means if people run hg inside different PID namespaces with a same UTS namespae, the lock would be broken - an hg proccess in pid namespace A will think the lock having a "random" pid in pid namespace B is "dead" and remove it. This patch solves the above issue by appending an PID namespace identifier of the current process to the lock prefix ("hostname"). It depends on /proc being mounted properly. But I don't think there is a better way to get pid namespace identifier reliably.

lock: move lock._host calculation to a function This allows customization per platform. See the next patch for why.

debugcommands: move 'debugknown' in the new module

debugcommands: extract debuginstall in the debugcommands module

dispatch: load debugcommand before extension Multiple extension will manipulate commands on load, we need the debug command to be loaded before that point.

merge with stable

bundle2: fix assertion that 'compression' hasn't been set `n.lower()` will return `compression`, not `Compression`.