push: move `incoming` into the push object

The fact that there is some unknown changes on remote one of the result of
discovery. It is then used by some push validation logic.

We move it in the object to be able to extract the said logic.

mercurial/exchange.py

@@ -46,6 +46,8 b' class pushoperation(object):'
         self.outgoing = None
         # all remote heads before the push
         self.remoteheads = None
+        # testable as a boolean indicating if any nodes are missing locally.
+        self.incoming = None
 
 def push(repo, remote, force=False, revs=None, newbranch=False):
     '''Push outgoing changesets (limited by revs) from a local
@@ -107,6 +109,7 b' def push(repo, remote, force=False, revs'
                            commoninc=commoninc, force=pushop.force)
             pushop.outgoing = outgoing
             pushop.remoteheads = remoteheads
+            pushop.incoming = inc
 
 
             if not outgoing.missing:
@@ -140,7 +143,7 b' def push(repo, remote, force=False, revs'
                     newbm = pushop.ui.configlist('bookmarks', 'pushing')
                     discovery.checkheads(unfi, pushop.remote, outgoing,
                                          remoteheads, pushop.newbranch,
-                                         bool(inc), newbm)
+                                         bool(pushop.incoming), newbm)
                 _pushchangeset(pushop)
             _pushsyncphase(pushop)
             _pushobsolete(pushop)