discovery: don't report all "unsynced" remote heads (issue4230)

8a9e0b523d2d made discovery more helpful - too helpful for some extreme use
cases.

Instead, we arbitrarily limit the list it at 4 and add 'or more'.

mercurial/discovery.py

@@ -313,7 +313,11 b' def checkheads(repo, remote, outgoing, r'
             newhs = candidate_newhs
         unsynced = sorted(h for h in unsyncedheads if h not in discardedheads)
         if unsynced:
-            heads = ' '.join(short(h) for h in unsynced)
+            if len(unsynced) <= 4 or repo.ui.verbose:
+                heads = ' '.join(short(h) for h in unsynced)
+            else:
+                heads = (' '.join(short(h) for h in unsynced[:4]) +
+                         ' ' + _("and %s others") % (len(unsynced) - 4))
             if branch is None:
                 repo.ui.status(_("remote has heads that are "
                                  "not known locally: %s\n") % heads)

tests/test-push-warn.t

@@ -378,7 +378,7 b' Pushing multi headed new branch:'
   added 3 changesets with 3 changes to 1 files (+1 heads)
 
 Checking prepush logic does not allow silently pushing
-multiple new heads:
+multiple new heads but also doesn't report too many heads:
 
   $ cd ..
   $ hg init h
@@ -404,10 +404,29 b' multiple new heads:'
   adding c
   created new head
 
+  $ for i in `seq 3`; do hg -R h up -q 0; echo $i > h/b; hg -R h ci -qAm$i; done
+
   $ hg -R i push h
   pushing to h
   searching for changes
-  remote has heads on branch 'default' that are not known locally: ce4212fc8847
+  remote has heads on branch 'default' that are not known locally: 534543e22c29 764f8ec07b96 afe7cc7679f5 ce4212fc8847
+  abort: push creates new remote head 97bd0c84d346!
+  (pull and merge or see "hg help push" for details about pushing new heads)
+  [255]
+  $ hg -R h up -q 0; echo x > h/b; hg -R h ci -qAmx
+  $ hg -R i push h
+  pushing to h
+  searching for changes
+  remote has heads on branch 'default' that are not known locally: 18ddb72c4590 534543e22c29 764f8ec07b96 afe7cc7679f5 and 1 others
+  abort: push creates new remote head 97bd0c84d346!
+  (pull and merge or see "hg help push" for details about pushing new heads)
+  [255]
+  $ hg -R i push h -v
+  pushing to h
+  searching for changes
+  remote has heads on branch 'default' that are not known locally: 18ddb72c4590 534543e22c29 764f8ec07b96 afe7cc7679f5 ce4212fc8847
+  new remote heads on branch 'default':
+   97bd0c84d346
   abort: push creates new remote head 97bd0c84d346!
   (pull and merge or see "hg help push" for details about pushing new heads)
   [255]