manifest: simplify manifest.add() by making args required

I verified that changed was never false (it was always a 2-tuple) by
adding

@@ -220,6 +225,8 @@ class manifest(revlog.revlog):

     def add(self, map, transaction, link, p1=None, p2=None,
             changed=None):
+        if not changed:
+            assert False, 'changed was %r' % changed
         # if we're using the cache, make sure it is valid and
         # parented by the same node we're diffing against
         if not (changed and p1 and (p1 in self._mancache)):

and observing that the test suite still passed. Making all the
arguments required should help future readers understand what's going
on here.

mercurial/localrepo.py

@@ -1415,7 +1415,7 b' class localrepository(object):'
                 for f in drop:
                     del m1[f]
                 mn = self.manifest.add(m1, trp, linkrev, p1.manifestnode(),
-                                       p2.manifestnode(), (new, drop))
+                                       p2.manifestnode(), new, drop)
                 files = changed + removed
             else:
                 mn = p1.manifestnode()

mercurial/manifest.py

@@ -159,11 +159,10 b' class manifest(revlog.revlog):'
         f, n = l.split('\0')
         return revlog.bin(n[:40]), n[40:-1]
 
-    def add(self, map, transaction, link, p1=None, p2=None,
-            changed=None):
+    def add(self, map, transaction, link, p1, p2, added, removed):
         # if we're using the cache, make sure it is valid and
         # parented by the same node we're diffing against
-        if not (changed and p1 and (p1 in self._mancache)):
+        if not (p1 and (p1 in self._mancache)):
             files = sorted(map)
             _checkforbidden(files)
 
@@ -175,7 +174,6 b' class manifest(revlog.revlog):'
             arraytext = array.array('c', text)
             cachedelta = None
         else:
-            added, removed = changed
             addlist = self._mancache[p1][1]
 
             _checkforbidden(added)