checkheads: take future obsoleted heads into account

If we push some successors they will likely create a new head on
remote. However as the obsoleted head will disappear after the push we
are not really increasing the number of heads.

There is several case which will lead to extra being actually pushed. But this
first changeset aims to be simple. See the inline comment for details.

Without this change, you need to push --force every time you want to
push a newer version which is very error prone.

The remote side still display +n heads on unbundle because it does not have the
obsolete marker at unbundle time.

mercurial/discovery.py

@@ -7,7 +7,7 b''
 
 from node import nullid, short
 from i18n import _
-import util, setdiscovery, treediscovery, phases
+import util, setdiscovery, treediscovery, phases, obsolete
 
 def findcommonincoming(repo, remote, heads=None, force=False):
     """Return a tuple (common, anyincoming, heads) used to identify the common
@@ -266,6 +266,7 b' def checkheads(repo, remote, outgoing, r'
     # error message, depending on unsynced status, is displayed.
     error = None
     unsynced = False
+    allmissing = set(outgoing.missing)
     for branch, heads in headssum.iteritems():
         if heads[0] is None:
             # Maybe we should abort if we push more that one head
@@ -274,8 +275,34 b' def checkheads(repo, remote, outgoing, r'
         if heads[2]:
             unsynced = True
         oldhs = set(heads[0])
-        newhs = set(heads[1])
+        candidate_newhs = set(heads[1])
+        # add unsynced data
+        oldhs.update(heads[2])
+        candidate_newhs.update(heads[2])
         dhs = None
+        if repo.obsstore:
+            # remove future heads which are actually obsolete by another
+            # pushed element:
+            #
+            # XXX There is several case this case does not handle properly
+            #
+            # (1) if <nh> is public, it won't be affected by obsolete marker
+            #     and a new is created
+            #
+            # (2) if the new heads have ancestors which are not obsolete and
+            #     not ancestors of any other heads we will have a new head too.
+            #
+            # This two case will be easy to handle for know changeset but much
+            # more tricky for unsynced changes.
+            newhs = set()
+            for nh in candidate_newhs:
+                for suc in obsolete.anysuccessors(repo.obsstore, nh):
+                    if suc != nh and suc in allmissing:
+                        break
+                else:
+                    newhs.add(nh)
+        else:
+            newhs = candidate_newhs
         if len(newhs) > len(oldhs):
             # strip updates to existing remote heads from the new heads list
             dhs = list(newhs - bookmarkedheads - oldhs)

tests/test-obsolete.t

@@ -357,3 +357,50 b' no warning displayed'
   searching for changes
   no changes found
   [1]
+
+Do not warn about new head when the new head is a successors of a remote one
+
+  $ hg glog
+  @  changeset:   5:6e572121998e
+  |  tag:         tip
+  |  user:        test
+  |  date:        Thu Jan 01 00:00:00 1970 +0000
+  |  summary:     add original_e
+  |
+  x  changeset:   4:7c694bff0650
+  |  user:        test
+  |  date:        Thu Jan 01 00:00:00 1970 +0000
+  |  summary:     add original_d
+  |
+  o  changeset:   3:5601fb93a350
+  |  parent:      1:7c3bad9141dc
+  |  user:        test
+  |  date:        Thu Jan 01 00:00:00 1970 +0000
+  |  summary:     add new_3_c
+  |
+  | o  changeset:   2:245bde4270cd
+  |/   user:        test
+  |    date:        Thu Jan 01 00:00:00 1970 +0000
+  |    summary:     add original_c
+  |
+  o  changeset:   1:7c3bad9141dc
+  |  user:        test
+  |  date:        Thu Jan 01 00:00:00 1970 +0000
+  |  summary:     add b
+  |
+  o  changeset:   0:1f0dee641bb7
+     user:        test
+     date:        Thu Jan 01 00:00:00 1970 +0000
+     summary:     add a
+  
+  $ hg up -q 'desc(new_3_c)'
+  $ mkcommit obsolete_e
+  created new head
+  $ hg debugobsolete `getid 'original_e'` `getid 'obsolete_e'`
+  $ hg push ../tmpf
+  pushing to ../tmpf
+  searching for changes
+  adding changesets
+  adding manifests
+  adding file changes
+  added 1 changesets with 1 changes to 1 files (+1 heads)