--- a/mercurial/revlogutils/constants.py	Mon Nov 28 18:58:35 2022 +0100
+++ b/mercurial/revlogutils/constants.py	Mon Nov 07 22:12:59 2022 -0500
@@ -301,3 +301,17 @@
 
 
 SPARSE_REVLOG_MAX_CHAIN_LENGTH = 1000
+
+### What should be done with a cached delta and its base ?
+
+# Ignore the cache when considering candidates.
+#
+# The cached delta might be used, but the delta base will not be scheduled for
+# usage earlier than in "normal" order.
+DELTA_BASE_REUSE_NO = 0
+
+# Prioritize trying the cached delta base
+#
+# The delta base will be tested for validy first. So that the cached deltas get
+# used when possible.
+DELTA_BASE_REUSE_TRY = 1