dagutil: remove heads() and localsubset from revlogdag.__init__

The previous commit removed the last consumer of this API.

I'm not going to mark as API incompatible because I doubt anybody
used this functionality (outside of possibly passing an argument
to revlogdag.__init__). I intend to remove revlogdag later in
this series and its API annotation will cover this one.

Differential Revision: https://phab.mercurial-scm.org/D4320

mercurial/dagutil.py

@@ -24,10 +24,6 b' class basedag(object):'
     def __init__(self):
         self._inverse = None
 
-    def heads(self):
-        '''list of head ixs'''
-        raise NotImplementedError
-
     def parents(self, ix):
         '''list of parents ixs of ix'''
         raise NotImplementedError
@@ -65,22 +61,12 b' class revlogbaseddag(basedag):'
     def __init__(self, revlog):
         basedag.__init__(self)
         self._revlog = revlog
-        self._heads = None
-
-    def heads(self):
-        if self._heads is None:
-            self._heads = self._getheads()
-        return self._heads
 
 class revlogdag(revlogbaseddag):
     '''dag interface to a revlog'''
 
-    def __init__(self, revlog, localsubset=None):
+    def __init__(self, revlog):
         revlogbaseddag.__init__(self, revlog)
-        self._heads = localsubset
-
-    def _getheads(self):
-        return [r for r in self._revlog.headrevs() if r != nullrev]
 
     def parents(self, ix):
         rlog = self._revlog
@@ -173,10 +159,6 b' class inverserevlogdag(revlogbaseddag, g'
             rev -= 1
         self._walkfrom = rev
 
-    def _getheads(self):
-        self._walkto(nullrev)
-        return self._roots
-
     def parents(self, ix):
         if ix is None:
             return []

mercurial/setdiscovery.py

@@ -152,7 +152,7 b' def findcommonheads(ui, local, remote,'
     else:
         ownheads = [rev for rev in cl.headrevs() if rev != nullrev]
 
-    dag = dagutil.revlogdag(cl, localsubset=ownheads)
+    dag = dagutil.revlogdag(cl)
 
     # early exit if we know all the specified remote heads already
     ui.debug("query 1; heads\n")