rust: Use the DisplayBytes trait in config printing
This is similar to `std::fmt::Display`, but for arbitrary bytes instead
of Unicode. Writing to an abstract output stream helps avoid allocating
intermediate `Vec<u8>` buffers.
Differential Revision: https://phab.mercurial-scm.org/D9966
== New Features ==
* `hg purge` is now a core command using `--confirm` by default.
* The `rev-branch-cache` is now updated incrementally whenever changesets
are added.
== New Experimental Features ==
* There's a new `diff.merge` config option to show the changes
relative to an automerge for merge changesets. This makes it
easier to detect and review manual changes performed in merge
changesets. It is supported by `hg diff --change`, `hg log -p`
`hg incoming -p`, and `hg outgoing -p` so far.
== Bug Fixes ==
== Backwards Compatibility Changes ==
== Internal API Changes ==
* `changelog.branchinfo` is deprecated and will be removed after 5.8.
It is superseded by `changelogrevision.branchinfo`.