== New Features ==

 * `hg config` now has a `--source` option to show where each

   configuration value comes from.

 * Introduced a command (debug-repair-issue6528) to repair repositories affected

   by issue6528 where certain files would show up as modified even if they were

   clean due to an issue in the copy-tracing code.

== Default Format Change ==

These changes affect newly created repositories (or new clone) done with

Mercurial 5.9.

== New Experimental Features ==

 * A `changelogv2` format has been introduced. It is not ready for use yet, but

   will be used later to address some of the weaknesses of the current revlog

   format.

 * Initial experiment and support for `dirstatev2`, a new dirstate format that

   addresses some of the weaknesses of the current dirstate format. Python + C

   and Rust support are being implemented, but the Rust solution is the one

   currently getting the attention for performance.

 * Initial support for `rhg status`. `rhg` is the Rust wrapper executable for hg

   that shortcuts some commands for faster execution speed.

== Bug Fixes ==

 * Fixed committing empty files with `narrow`

 * Allow overriding `pip`'s pep517 compliance to build C or Rust extensions

 * Fixed regression on outgoing email when not specifying revisions

 * Fixed a regression causing bookmarks to disappear when using Rust persistent nodemap

 * Fixed a regression (in 5.9.1) introduced in 5.9 when cloning repos with

   deep filenames

 * Fixed detection of directories becoming symlinks, but only when using the

   Rust extensions.

 * Fixed ignore and include not composing in the Rust status

 * `hg commit --interactive` now handles deselecting edits of a rename

 * Fixed a case where `hg evolve` gives different results when interrupted

 * Fixed a memory leak in phases computation

 * `histedit` and `shelve` don't swallow errors when updating the working copy

   anymore

 * Improve error message when detecting content-divergence with a hidden

   common predecessor

 * No longer re-order parents in filelog, see issue6533

 * Fix revisions affected by issue6533 on the fly during exchange

 * Many Windows fixes for stability and py3 compatibility improvements

 * Many other miscellaneous fixes

== Backwards Compatibility Changes ==

== Internal API Changes ==

The Dirstate API have been updated as the previous function leaked some

internal details and did not distinguish between two important cases: "We are

changing parent and need to adjust the dirstate" and "some command is changing

which file is tracked". To clarify the situation:

* the following functions have been deprecated,

  - `dirstate.add`,

  - `dirstate.normal`,

  - `dirstate.normallookup`,

  - `dirstate.merge`,

  - `dirstate.otherparent`,

  - `dirstate.remove`,

  - `dirstate.drop`,

  - `dirstateitem.__getitem__`,

* these new functions are added for the "adjusting parents" use-case:

  - `dirstate.update_file`,

  - `dirstate.update_file_p1`,

* these new function are added for the "adjusting wc file" use-case":

  - `dirstate.set_tracked`,

  - `dirstate.set_untracked`,

  - `dirstate.set_clean`,

  - `dirstate.set_possibly_dirty`,

See inline documentation of the new functions for details.

* Additionally, the following have been deprecated:

  - `urlutil.getpath` function

  - `localrepository.updatecaches`' `full` argument

* The following have been removed:

  - `revlog.revlogio` has been removed