relnotes/5.3

ci: add a runner for macos

This is running from a venv, created with the packages from the requirements
file in the `test-setup-future-work` topic being discussed separately.  We can
basically reuse the existing `test_c` configuration as-is, but there was one
small issue- if the clone from the previous CI run is still present in `/tmp`,
the clone for the current run fails.  It's not a problem for the current setup
because a new container is instantiated, so the easy fix is to simply delete the
clone first.  (The Windows CI avoids this by not cloning in the first place.)

It looks like it takes ~80m to run the whole test suite on the current system.

== New Features ==

 * Windows will process hgrc files in %PROGRAMDATA%\Mercurial\hgrc.d.


== New Experimental Features ==


== Bug Fixes  ==

 * The `indent()` template function was documented to not indent empty lines,
   but it still indented the first line even if it was empty. It no longer does
   that.

== Backwards Compatibility Changes ==


== Internal API Changes ==

 * Matcher instances no longer have a `explicitdir` property. Consider
   rewriting your code to use `repo.wvfs.isdir()` and/or
   `ctx.hasdir()` instead. Also, the `traversedir` property is now
   also called when only `explicitdir` used to be called. That may
   mean that you can simply remove the use of `explicitdir` if you
   were already using `traversedir`.

 * The `revlog.nodemap` object have been merged into the `revlog.index` object.
   * `n in revlog.nodemap` becomes `revlog.index.has_node(n)`,
   * `revlog.nodemap[n]` becomes `revlog.index.rev(n)`,
   * `revlog.nodemap.get(n)` becomes `revlog.index.get_rev(n)`.

 * `copies.duplicatecopies()` was renamed to
   `copies.graftcopies()`. Its arguments changed from revision numbers
   to context objects. It also lost its `repo` and `skip` arguments
   (they should no longer be needed).