keepalive: honor urllib2 style get_method overrides In urllib2 docs and discussions it can be found that in order to make a request other than GET or POST the get_method of a Request object can be overriden. Make Mercurial's internal version of this honor the return value of get_method. Please see the followup patch to the bugzilla extension for the reason for this change. Marking RFC because I'm not entirely sure this is the right way make the HTTP requests.

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

localrepo: avoid unnecessary sorting headrevs output already sorted, no need to sort it again.

localrepo: cache self.changelog in local variable Repeated self.changelog lookups can incur overhead. Let's cache it in the separate variable.

destutil: remove dead code about non-linear updates IIUC, the non-linear updates no longer happen by default since 6b1fc09c699a (update: change default destination to tipmost descendant (issue4673) (BC), 2016-02-02), and it was only if they happened by default that we used to error out, so there is no longer a need to handle this case.