--- a/mercurial/filelog.py	Thu Aug 09 19:30:36 2018 -0700
+++ b/mercurial/filelog.py	Thu Aug 09 19:27:54 2018 -0700
@@ -76,9 +76,6 @@
     def deltaparent(self, rev):
         return self._revlog.deltaparent(rev)
 
-    def candelta(self, baserev, rev):
-        return self._revlog.candelta(baserev, rev)
-
     def iscensored(self, rev):
         return self._revlog.iscensored(rev)
 

--- a/mercurial/repository.py	Thu Aug 09 19:30:36 2018 -0700
+++ b/mercurial/repository.py	Thu Aug 09 19:27:54 2018 -0700
@@ -552,9 +552,6 @@
     def deltaparent(rev):
         """"Return the revision that is a suitable parent to delta against."""
 
-    def candelta(baserev, rev):
-        """"Whether a delta can be generated between two revisions."""
-
 class ifiledata(interfaceutil.Interface):
     """Storage interface for data storage of a specific file.
 

--- a/tests/simplestorerepo.py	Thu Aug 09 19:30:36 2018 -0700
+++ b/tests/simplestorerepo.py	Thu Aug 09 19:27:54 2018 -0700
@@ -241,7 +241,7 @@
         p1node = self.parents(self.node(rev))[0]
         return self.rev(p1node)
 
-    def candelta(self, baserev, rev):
+    def _candelta(self, baserev, rev):
         validaterev(baserev)
         validaterev(rev)
 
@@ -527,7 +527,7 @@
                 # for choosing a delta parent.
                 baserev = self.deltaparent(rev)
 
-                if baserev != nullrev and not self.candelta(baserev, rev):
+                if baserev != nullrev and not self._candelta(baserev, rev):
                     baserev = nullrev
 
             revision = None