# HG changeset patch
# User Pierre-Yves David <pierre-yves.david@octobus.net>
# Date 1610580820 -3600
# Node ID a18e256c4d3b99987d5631e18b7386b3385b8a38
# Parent  599d247af6001bb0e8278cf9384a359ea0b74f6e
persistent-nodemap: document the `devel.persistent-nodemap` option

What it does is not obvious.

Differential Revision: https://phab.mercurial-scm.org/D9753

diff -r 599d247af600 -r a18e256c4d3b mercurial/configitems.py
--- a/mercurial/configitems.py	Fri Jan 15 23:47:16 2021 +0100
+++ b/mercurial/configitems.py	Thu Jan 14 00:33:40 2021 +0100
@@ -635,6 +635,8 @@
     b'legacy.exchange',
     default=list,
 )
+# When True, revlogs use a special reference version of the nodemap, that is not
+# performant but is "known" to behave properly.
 coreconfigitem(
     b'devel',
     b'persistent-nodemap',