repository: remove candelta() from ifileindex

candelta() was previously called by changegroup code. With delta
generation moved to the storage API, there are no more external
consumers of this method and it can be removed from the storage
interface.

Differential Revision: https://phab.mercurial-scm.org/D4236

mercurial/filelog.py

@@ -76,9 +76,6 class filelog(object):
     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)
 

mercurial/repository.py

@@ -552,9 +552,6 class ifileindex(interfaceutil.Interface
     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.
 

tests/simplestorerepo.py

@@ -241,7 +241,7 class filestorage(object):
         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 class filestorage(object):
                 # 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