phase: properly compute ancestors of --rev on push (issue3786)

Now that discovery is working on unfiltered changeset, I had a good occasion to
look at that bug again. This let me realise that a trivial node vs rev
comparision was the cause of this two years old bugs…

Happy second birthday phases!

mercurial/localrepo.py

@@ -1899,7 +1899,8 b' class localrepository(object):'
                     # We can pick:
                     # * missingheads part of common (::commonheads)
                     common = set(outgoing.common)
-                    cheads = [node for node in revs if node in common]
+                    nm = self.changelog.nodemap
+                    cheads = [node for node in revs if nm[node] in common]
                     # and
                     # * commonheads parents on missing
                     revset = unfi.set('%ln and parents(roots(%ln))',

tests/test-phases-exchange.t

@@ -92,6 +92,20 b' push from alpha to beta should update ph'
   |
   o  0 public a-A - 054250a37db4
   
+  $ hg push -r 2 ../beta
+  pushing to ../beta
+  searching for changes
+  no changes found
+  [1]
+  $ hgph
+  @  3 draft a-D - b555f63b6063
+  |
+  o  2 public a-C - 54acac6f23ab
+  |
+  o  1 public a-B - 548a3d25dbf0
+  |
+  o  0 public a-A - 054250a37db4
+  
   $ hg push ../beta
   pushing to ../beta
   searching for changes