--- a/hgext3rd/evolve/stablerange.py	Sun Mar 19 03:07:01 2017 +0100
+++ b/hgext3rd/evolve/stablerange.py	Sun Mar 19 04:39:00 2017 +0100
@@ -236,6 +236,43 @@
         # this class reach.
         return self._subrangescache.get(rangeid)
 
+    def _slicesrangeat(self, repo, rangeid, globalindex):
+        localindex = globalindex - rangeid.index
+
+        cl = repo.changelog
+
+        result = []
+        bottom = rangeid._revs[:localindex]
+        top = stablerange(repo, rangeid.head, globalindex, rangeid._revs[localindex:])
+        #
+        toprootdepth = repo.stablerange.depthrev(repo, top._revs[0])
+        if toprootdepth + len(top) == rangeid.depth + 1:
+            bheads = [bottom[-1]]
+        else:
+            bheads = set(bottom)
+            parentrevs = cl.parentrevs
+            du = bheads.difference_update
+            for r in bottom:
+                du(parentrevs(r))
+            # if len(bheads) == 1:
+            #     assert 1 == len(repo.revs('roots(%ld)', top._revs))
+        if len(bheads) == 1:
+            newhead = bottom[-1]
+            bottomdepth = repo.stablerange.depthrev(repo, newhead)
+            newstart = bottomdepth - len(bottom)
+            result.append(stablerange(repo, newhead, newstart, bottom))
+        else:
+            # assert 1 < len(bheads), (toprootdepth, len(top), len(rangeid))
+            cl = repo.changelog
+            for h in bheads:
+                subset = cl.ancestors([h], inclusive=True)
+                hrevs = [r for r in bottom if r in subset]
+                start = repo.stablerange.depthrev(repo, h) - len(hrevs)
+                entry = stablerange(repo, h, start, [r for r in bottom if r in subset])
+                result.append(entry)
+        result.append(top)
+        return result
+
 def _hlp2(i):
     """return highest power of two lower than 'i'"""
     return 2 ** int(math.log(i - 1, 2))
@@ -287,45 +324,9 @@
         assert len(r) == len(self), (self.head, self.index, len(r), len(self))
         return r
 
-    def _slicesat(self, globalindex):
-        localindex = globalindex - self.index
-
-        cl = self._repo.changelog
-
-        result = []
-        bottom = self._revs[:localindex]
-        top = stablerange(self._repo, self.head, globalindex, self._revs[localindex:])
-        #
-        toprootdepth = self._repo.stablerange.depthrev(self._repo, top._revs[0])
-        if toprootdepth + len(top) == self.depth + 1:
-            bheads = [bottom[-1]]
-        else:
-            bheads = set(bottom)
-            parentrevs = cl.parentrevs
-            du = bheads.difference_update
-            for r in bottom:
-                du(parentrevs(r))
-            # if len(bheads) == 1:
-            #     assert 1 == len(self._repo.revs('roots(%ld)', top._revs))
-        if len(bheads) == 1:
-            newhead = bottom[-1]
-            bottomdepth = self._repo.stablerange.depthrev(self._repo, newhead)
-            newstart = bottomdepth - len(bottom)
-            result.append(stablerange(self._repo, newhead, newstart, bottom))
-        else:
-            # assert 1 < len(bheads), (toprootdepth, len(top), len(self))
-            cl = self._repo.changelog
-            for h in bheads:
-                subset = cl.ancestors([h], inclusive=True)
-                hrevs = [r for r in bottom if r in subset]
-                start = self._repo.stablerange.depthrev(self._repo, h) - len(hrevs)
-                entry = stablerange(self._repo, h, start, [r for r in bottom if r in subset])
-                result.append(entry)
-        result.append(top)
-        return result
-
     def subranges(self):
-        cached = self._repo.stablerange.subranges(self._repo, self)
+        cache = self._repo.stablerange
+        cached = cache.subranges(self._repo, self)
         if cached is not None:
             return cached
         step = _hlp2(self.depth)
@@ -340,7 +341,7 @@
         else:
             assert standard_start < self.depth
             slicepoint = standard_start
-        result = self._slicesat(slicepoint)
+        result = cache._slicesrangeat(self._repo, self, slicepoint)
         self._repo.stablerange.setsubranges(self, result)
         return result