--- a/hgext/evolve.py	Fri Jun 19 10:47:02 2015 -0700
+++ b/hgext/evolve.py	Fri Jun 19 11:03:51 2015 -0700
@@ -1950,6 +1950,10 @@
         if not precs:
             raise util.Abort('nothing to prune')
 
+        if not obsolete.isenabled(repo, obsolete.allowunstableopt):
+            if len(repo.revs("(%ld::) - %ld", revs, revs)) != 0:
+                raise util.Abort(_("cannot prune in the middle of a stack"))
+
         # defines successors changesets
         sucs = scmutil.revrange(repo, succs)
         sucs.sort()