upgrade: move optimisation to something more declarative
This is not great yet, but still better than the previous state. This get use
one step closer to having all the possible "actions" clearly declared and moved
in a dedicated module.
Differential Revision: https://phab.mercurial-scm.org/D9475
== 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 ==