revlog: move tiprev() from changelog up to revlog

This makes the changelog override simpler and it seems more
consistent.

Differential Revision: https://phab.mercurial-scm.org/D7250

mercurial/changelog.py

@@ -406,14 +406,11 b' class changelog(revlog.revlog):'
         self._copiesstorage = opener.options.get(b'copies-storage')
 
     def tiprev(self):
+        """filtered version of revlog.tiprev"""
         for i in pycompat.xrange(len(self) - 1, -2, -1):
             if i not in self.filteredrevs:
                 return i
 
-    def tip(self):
-        """filtered version of revlog.tip"""
-        return self.node(self.tiprev())
-
     def __contains__(self, rev):
         """filtered version of revlog.__contains__"""
         return 0 <= rev < len(self) and rev not in self.filteredrevs

mercurial/revlog.py

@@ -593,8 +593,11 b' class revlog(object):'
             with func() as fp:
                 yield fp
 
+    def tiprev(self):
+        return len(self.index) - 1
+
     def tip(self):
-        return self.node(len(self.index) - 1)
+        return self.node(self.tiprev())
 
     def __contains__(self, rev):
         return 0 <= rev < len(self)