Mercurial 5.8 (2021-05-01)#

This is an overview of the 5.8 release.

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.
The new options experimental.bundlecompthreads and experimental.bundlecompthreads.<engine> can be used to instruct the compression engines for bundle operations to use multiple threads for compression. The default is single threaded operation. Currently only supported for zstd.

These changes affects newly created repositories (or new clone) done with Mercurial 5.8.

The ZSTD compression will now be used by default for new repositories when available. This compression format was introduced in Mercurial 5.0, released in May 2019. See hg help config.format.revlog-compression for details.
Mercurial installation built with the Rust parts will now use the “persistent nodemap” feature by default. This feature was introduced in Mercurial 5.4 (May 2020). However Mercurial instalation built without the fast Rust implementation will refuse to interract with them by default. This restriction can be lifted through configuration.

See hg help config.format.use-persistent-nodemap for details

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.

In normal repositories, the first parent of a changeset is not null, unless both parents are null (like the first changeset). Some legacy repositories violate this condition. The revlog code will now silentely swap the parents if this condition is tested. This can change the output of hg log when explicitly asking for first or second parent. The changesets “nodeid” are not affected.

changelog.branchinfo is deprecated and will be removed after 5.8. It is superseded by changelogrevision.branchinfo.
Callbacks for revlog.addgroup and the changelog._nodeduplicatecallback hook now get a revision number as argument instead of a node.
revlog.addrevision returns the revision number instead of the node.
nodes.nullid and related constants are being phased out as part of the deprecation of SHA1. Repository instances and related classes provide access via nodeconstants and in some cases nullid attributes.