--- a/hgext3rd/evolve/obshistory.py	Thu Jan 11 17:54:34 2018 +0530
+++ b/hgext3rd/evolve/obshistory.py	Thu Jan 11 18:07:09 2018 +0530
@@ -163,13 +163,11 @@
 
     return True, succ
 
-def getmarkerdescriptionpatch(repo, base, succ):
-    basectx = repo[base]
-    succctx = repo[succ]
+def getmarkerdescriptionpatch(repo, basedesc, succdesc):
     # description are stored without final new line,
     # add one to avoid ugly diff
-    basedesc = basectx.description() + '\n'
-    succdesc = succctx.description() + '\n'
+    basedesc += '\n'
+    succdesc += '\n'
 
     # fake file name
     basename = "changeset-description"
@@ -496,13 +494,17 @@
         if _patchavailable[0] is True:
             succ = _patchavailable[1]
 
+            basectx = repo[node]
+            succctx = repo[succ]
             # Description patch
-            descriptionpatch = getmarkerdescriptionpatch(repo, node, succ)
+            descriptionpatch = getmarkerdescriptionpatch(repo,
+                                                         basectx.description(),
+                                                         succctx.description())
 
             if descriptionpatch:
                 # add the diffheader
                 diffheader = "diff -r %s -r %s changeset-description\n" % \
-                             (repo[node], repo[succ])
+                             (basectx, succctx)
                 descriptionpatch = diffheader + descriptionpatch
 
                 def tolist(text):