--- a/hgext3rd/evolve/stablerangecache.py	Sun May 03 20:11:37 2020 +0800
+++ b/hgext3rd/evolve/stablerangecache.py	Sun May 03 01:45:04 2020 +0200
@@ -234,6 +234,7 @@
 
     def _setsub(self, rangeid, value):
         assert rangeid not in self._unsavedsubranges
+        assert 0 <= rangeid[1] <= rangeid[0], rangeid
         self._unsavedsubranges[rangeid] = value
         super(stablerangesqlbase, self)._setsub(rangeid, value)