revlog: add a C implementation of `headrevsdiff` Python implementation of `headrevsdiff` can be very slow in the worst case compared with the `heads` computation it replaces, since the latter is done in C. Even the average case of this Python implementation is still noticeable in the profiles. This patch makes the computation much much faster by doing it in C.

unbundle: faster computation of changed heads To compute the set of changed heads it's sufficient to look at the recent commits, instead of looking at all heads currently in existence.

branching: merge stable into default

hg-core: separate timestamp and extra methods

debugformat: fix formatting for compression level `bytes(<int>)` gives a very different result as `str(<int>)` and the display of `hg debugformat` have been broken for a while as a result.

hg-core: implement timestamp line parsing

doc: document that labels must have a dot in them to have an effect I noticed that the `hg topics` template has a bare `topic` label with no dot, and that makes it useless, as such a label will never receive any effect by the colour extension. This dot has been required for a long time, at least since 2011, but we never formally documented it!

tests: tweak chg test to make it fail less often the test apparently sometimes prints the word "start" as a part of profile, so let's no longer match "start": CHGHG=/*/install/bin/hg (glob) + \x1b[90m | 50.0% 0.01s profiling.py: __enter__ line 196: self.start()\x1b[0m (esc) + \x1b[90m | 50.0% 0.01s profiling.py: start line 261: self._profiler.__enter__()\x1b[0m (esc) + \x1b[90m | 50.0% 0.01s profiling.py: statprofile line 125: statprof.start(mechanism=b'...\x1b[0m (esc) + \x1b[90m | 50.0% 0.01s statprof.py: start line 356: state.thread.start()\x1b[0m (esc) + \x1b[90m | 50.0% 0.01s threading.py: start line 852: self._started.wait()\x1b[0m (esc)

cext: fix potential memory leaks of list items appended with PyList_Append Also reduce the duplication in the tricky code that uses PyList_Append by extracting it into a function `pylist_append_owned`.

crecord: enable search hotkeys (issue6834) The keys I chose here should be similar to less/vim keybindings, which should fit the overall keybinding theme of crecord.

crecord: add handle(next|prev)search functions These are now just simple wrappers around `searchdirection`

crecord: add a searchdirection function If a regex has already been previously set, this function handles the UI elements of searching again forward or backward.

crecord: add a handlesearch function This function sets up some of the UI, such as getting the search string from the user and displaying results or their absence.

crecord: add a showsearch function This function takes a regex and searches either forward or backward, moving the current item to the found item, if any, and unfolding the relevant context.

crecord: add a default regex to curseschunkselector Whether there is a regex to search or not will affect if we can find the next or the previous search hit.

crecord: add `content` properties to all nodes In order to have a unified API of what can be searched, let's provide a `content` property to each node type. This way we can search filenames, context headers (e.g. containing function names, if deducible from patch context) or changed lines themselves.