# HG changeset patch
# User Pierre-Yves David <pierre-yves.david@octobus.net>
# Date 2022-10-17 14:26:16
# Node ID 4bd12c0f531e8b15db2d7ff6d720374aea081706
# Parent  f56873a7284c7b7c2ad3dcdffcc449ee75df27ae

reuse-delta-base: improves some documentation

The current code got me a bit confused initially. So a bit more documentation
around it cannot hurt.

diff --git a/mercurial/configitems.py b/mercurial/configitems.py
--- a/mercurial/configitems.py
+++ b/mercurial/configitems.py
@@ -2075,6 +2075,7 @@ coreconfigitem(
     b'revlog.reuse-external-delta',
     default=True,
 )
+# This option is True unless `format.generaldelta` is set.
 coreconfigitem(
     b'storage',
     b'revlog.reuse-external-delta-parent',
diff --git a/mercurial/scmutil.py b/mercurial/scmutil.py
--- a/mercurial/scmutil.py
+++ b/mercurial/scmutil.py
@@ -1858,7 +1858,12 @@ def gdinitconfig(ui):
 
 
 def gddeltaconfig(ui):
-    """helper function to know if incoming delta should be optimised"""
+    """helper function to know if incoming deltas should be optimized
+
+    The `format.generaldelta` config is an old form of the config that also
+    implies that incoming delta-bases should be never be trusted. This function
+    exists for this purpose.
+    """
     # experimental config: format.generaldelta
     return ui.configbool(b'format', b'generaldelta')