--- a/hgext3rd/evolve/obsdiscovery.py
+++ b/hgext3rd/evolve/obsdiscovery.py
@@ -406,7 +406,36 @@
 
 def _obshashrange(repo, rangeid):
     """return the obsolete hash associated to a range"""
-    return rangeid.obshash
+    cache = repo.obsstore.rangeobshashcache
+    obshash = cache.get(rangeid)
+    if obshash is not None:
+        return obshash
+    pieces = []
+    nullid = node.nullid
+    if len(rangeid) == 1:
+        tmarkers = repo.obsstore.relevantmarkers([rangeid.node])
+        pieces = []
+        for m in tmarkers:
+            mbin = obsolete._fm1encodeonemarker(m)
+            pieces.append(mbin)
+        pieces.sort()
+    else:
+        for subrange in rangeid.subranges():
+            obshash = _obshashrange(repo, subrange)
+            if obshash != nullid:
+                pieces.append(obshash)
+
+    sha = hashlib.sha1()
+    # note: if there is only one subrange with actual data, we'll just
+    # reuse the same hash.
+    if not pieces:
+        obshash = node.nullid
+    elif len(pieces) != 1 or obshash is None:
+        sha = hashlib.sha1()
+        for p in pieces:
+            sha.update(p)
+        obshash = cache[rangeid] = sha.digest()
+    return obshash
 
 @eh.wrapfunction(obsolete.obsstore, '_addmarkers')
 def _addmarkers(orig, obsstore, *args, **kwargs):

--- a/hgext3rd/evolve/stablerange.py
+++ b/hgext3rd/evolve/stablerange.py
@@ -9,7 +9,6 @@
 
 import collections
 import math
-import hashlib
 
 from mercurial import (
     commands,
@@ -24,7 +23,6 @@
 
 from . import (
     exthelper,
-    obsolete,
 )
 
 eh = exthelper.exthelper()
@@ -387,39 +385,6 @@
     def subranges(self):
         return self._repo.stablerange.subranges(self._repo, self)
 
-    @util.propertycache
-    def obshash(self):
-        cache = self._repo.obsstore.rangeobshashcache
-        obshash = cache.get(self)
-        if obshash is not None:
-            return obshash
-        pieces = []
-        nullid = nodemod.nullid
-        if len(self) == 1:
-            tmarkers = self._repo.obsstore.relevantmarkers([self.node])
-            pieces = []
-            for m in tmarkers:
-                mbin = obsolete._fm1encodeonemarker(m)
-                pieces.append(mbin)
-            pieces.sort()
-        else:
-            for subrange in self.subranges():
-                obshash = subrange.obshash
-                if obshash != nullid:
-                    pieces.append(obshash)
-
-        sha = hashlib.sha1()
-        # note: if there is only one subrange with actual data, we'll just
-        # reuse the same hash.
-        if not pieces:
-            obshash = nodemod.nullid
-        elif len(pieces) != 1 or obshash is None:
-            sha = hashlib.sha1()
-            for p in pieces:
-                sha.update(p)
-            obshash = cache[self] = sha.digest()
-        return obshash
-
 @eh.reposetup
 def setupcache(ui, repo):