relnotes: elaborate on the side effects of hooks having HGPLAIN=1
Differential Revision: https://phab.mercurial-scm.org/D9943
--- a/relnotes/next Sun Jan 31 19:56:52 2021 -0500
+++ b/relnotes/next Mon Feb 01 15:37:03 2021 -0500
@@ -37,7 +37,11 @@
is also supported by "premerge" as
`merge-tools.<tool>.premerge=keep-mergediff`.
- * External hooks are now called with `HGPLAIN=1` preset.
+ * External hooks are now called with `HGPLAIN=1` preset. This has the side
+ effect of ignoring aliases, templates, revsetaliases, and a few other config
+ options in any `hg` command spawned by the hook. The previous behavior
+ can be restored by setting HGPLAINEXCEPT appropriately in the parent process.
+ See `hg help environment` for the list of items, and how to set it.
* The `branchmap` cache is updated more intelligently and can be
significantly faster for repositories with many branches and changesets.