relnotes: copy contents of "next" to "5.8" and clear "next"

The same procedure as every year^Wcycle.

Unlike previous cycles, I haven't actually recorded the copy because
we don't want to propagate further changes in "next" (from the stable
branch) to "5.8".

Differential Revision: https://phab.mercurial-scm.org/D10500

relnotes/5.8

@@ -0,0 +1,68 b''
+== 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.
+
+== Default Format Change ==
+
+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
+
+== 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 ==
+
+ * gracefully recover from inconsistent persistent-nodemap data from disk.
+
+
+== Backwards Compatibility Changes ==
+
+ * 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.
+
+
+== Internal API Changes ==
+
+ * `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.

relnotes/next

@@ -1,68 +1,21 b''
 == 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.
 
 == Default Format Change ==
 
 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
 
 == 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 ==
 
- * gracefully recover from inconsistent persistent-nodemap data from disk.
-
 
 == Backwards Compatibility Changes ==
 
- * 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.
-
 
 == Internal API Changes ==
 
- * `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.