--- a/mercurial/help/config.txt Wed Feb 27 10:49:25 2019 +0100
+++ b/mercurial/help/config.txt Wed Feb 27 12:40:18 2019 +0100
@@ -1865,6 +1865,22 @@
considered. Even when disabled, the existing delta from the source will be
reused if the same delta parent is selected.
+``revlog.reuse-external-delta``
+ Control the reuse of delta from external source.
+ (typically: apply bundle from `hg pull` or `hg push`).
+
+ New revisions are usually provided as a delta against another revision. By
+ default, Mercurial will not recompute the same delta again, trusting
+ externally provided deltas. There have been rare cases of small adjustment
+ to the diffing algorithm in the past. So in some rare case, recomputing
+ delta provided by ancient clients can provides better results. Disabling
+ this option means going through a full delta recomputation for all incoming
+ revisions. It means a large increase in CPU usage and will slow operations
+ down.
+
+ This option is enabled by default. When disabled, it also disables the
+ related ``storage.revlog.reuse-external-delta-parent`` option.
+
``server``
----------