relnotes/5.2

ui: refactor `readconfig()` into a form that can consume resources

The old form can't completely go away, because files outside of packages still
need to be read.  The name passed in here is a tuple of `package name, resource`
as needed by the resource API.

I like the idea of stating the config file is embedded in the executable by
listing is as `exe!package.resource`.  This would be consistent with how
`debuginstall` points to the executable for the python executable, lib, and
installed modules.  While in practice the filesystem path is available from the
backing ResourceReader when the resource is opened, it is a relative path on py2
and absolute on py3.  Further, while this would show in the `hg config` output
for each option if set as such here, it doesn't show in the `reading from...`
line when `--debug` is used.  The file isn't actually open where that prints, so
there's no way I see to get that info there.  So I opted for the simple prefix
to distinguish resources from files.

Differential Revision: https://phab.mercurial-scm.org/D7775

== New Features ==

 * The amend extension supports the `--currentuser` argument.

 * The amend extension supports the `--close-branch` argument.

 * The amend extension supports the `--secret` argument.

 * The uncommit extension supports the `rewrite.update-timestamp` config option.

== New Experimental Features ==


== Bug Fixes  ==


== Backwards Compatibility Changes ==

 * A shell that supports `$(command)`` syntax for command substitution is now
   required for running the test suite. The test runner normally uses
   `sh`, so if that is a shell that doesn't support `$(command)` syntax,
   you can override it by setting `$HGTEST_SHELL` or by passing it to
   `run-tests.py --shell <shell>`.

 * The (experimental) narrow extension's wire protocol changed. If
   you're using it, you'll need to make sure to upgrade server and
   client at the same time.

== Internal API Changes ==