== New Features ==

 * clonebundles can be annotated with the expected memory requirements

   using the `REQUIREDRAM` option. This allows clients to skip

   bundles created with large zstd windows and fallback to larger, but

   less demanding bundles.

 * The `phabricator` extension now provides more functionality of the

   arcanist CLI like changing the status of a differential.

 * Phases processing is much faster, especially for repositories with

   old non-public changesets.

== New Experimental Features ==

 * The core of some hg operations have been (and are being)

   implemented in rust, for speed. `hg status` on a repository with

   300k tracked files goes from 1.8s to 0.6s for instance.

   This has currently been tested only on linux, and does not build on

   windows. See rust/README.rst in the mercurial repository for

   instructions to opt into this.

 * An experimental config `rewrite.empty-successor` was introduced to control

   what happens when rewrite operations result in empty changesets.

== Bug Fixes ==

 * For the case when connected to a TTY, stdout was fixed to be line-buffered

   on Python 3 (where it was block-buffered before, causing the process to seem

   hanging) and Windows on Python 2 (where it was unbuffered before).

 * Subversion sources of the convert extension were fixed to work on Python 3.

 * Subversion sources of the convert extension now interpret the encoding of

   URLs like Subversion. Previously, there were situations where the convert

   extension recognized a repository as present but Subversion did not, and

   vice versa.

 * The empty changeset check of in-memory rebases was fixed to match that of

   normal rebases (and that of the commit command).

 * The push command now checks the correct set of outgoing changesets for

   obsolete and unstable changesets. Previously, it could happen that the check

   prevented pushing changesets which were already on the server.

== Backwards Compatibility Changes ==

 * Mercurial now requires at least Python 2.7.9 or a Python version that

   backported modern SSL/TLS features (as defined in PEP 466), and that Python

   was compiled against a OpenSSL version supporting TLS 1.1 or TLS 1.2

   (likely this requires the OpenSSL version to be at least 1.0.1).

 * The `hg perfwrite` command from contrib/perf.py was made more flexible and

   changed its default behavior. To get the previous behavior, run `hg perfwrite

   --nlines=100000 --nitems=1 --item='Testing write performance' --batch-line`.

 * The absorb extension now preserves changesets with no file changes that can

   be created by the commit command (those which change the branch name

   compared to the parent and those closing a branch head).

== Internal API Changes ==

 * logcmdutil.diffordiffstat() now takes contexts instead of nodes.

 * The `mergestate` class along with some related methods and constants have

   moved from `mercurial.merge` to a new `mercurial.mergestate` module.

 * The `phasecache` class now uses sparse dictionaries for the phase data.

   New accessors are provided to detect if any non-public changeset exists

   (`hasnonpublicphases`) and get the correponsponding root set

   (`nonpublicphaseroots`).

 * The `stdin`, `stdout` and `stderr` attributes of the `mercurial.pycompat`

   module were removed. Instead, the attributes of same name from the

   `mercurial.utils.procutil` module should be used, which provide more

   consistent behavior across Python versions and platforms.