dagutil: use a listcomp instead of a map()

In Python 3, the map() returns a generator object instead of a list,
and some parts of hg depend on this being consumable more than once or
sortable in place.

Differential Revision: https://phab.mercurial-scm.org/D1099

mercurial/dagutil.py

@@ -148,7 +148,7 b' class revlogbaseddag(basedag):'
                     if (r is not None
                         and r != nullrev
                         and r not in rl.filteredrevs)]
-        return map(self._internalize, ids)
+        return [self._internalize(i) for i in ids]
 
 
 class revlogdag(revlogbaseddag):