D9943: relnotes: elaborate on the side effects of hooks having HGPLAIN=1

[mharbison72 (Matt Harbison)]

mharbison72 created this revision.
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REPOSITORY
  rHG Mercurial

BRANCH
  stable

REVISION DETAIL
  https://phab.mercurial-scm.org/D9943

AFFECTED FILES
  relnotes/next

CHANGE DETAILS

diff --git a/relnotes/next b/relnotes/next
--- a/relnotes/next
+++ b/relnotes/next
@@ -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.



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