pull: don't suggest running hg merge when new heads are on different branches

After a pull when new heads are added but no head is added on the current
branch, the "run 'hg merge'" message can be misleading.  This patch doesn't
output the merge message in that scenario.

mercurial/commands.py

@@ -2989,7 +2989,10 b' def postincoming(ui, repo, modheads, opt'
         else:
             ui.status(_("not updating, since new heads added\n"))
     if modheads > 1:
-        ui.status(_("(run 'hg heads' to see heads, 'hg merge' to merge)\n"))
+        if (len(repo.branchheads()) > 1):
+            ui.status(_("(run 'hg heads' to see heads, 'hg merge' to merge)\n"))
+        else:
+            ui.status(_("(run 'hg heads' to see heads)\n"))
     else:
         ui.status(_("(run 'hg update' to get a working copy)\n"))
 

tests/test-pull-branch.t

@@ -134,3 +134,30 b' Should succeed because there is only one'
   not updating, since new heads added
   (run 'hg heads' to see heads, 'hg merge' to merge)
 
+Make changes on new branch on tt
+
+  $ hg branch branchC
+  marked working directory as branch branchC
+  $ echo b1 > bar 
+  $ hg ci -Am "commit on branchC"
+  adding bar
+
+Make changes on default branch on t
+
+  $ cd ../t
+  $ hg up -C default
+  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  $ echo a1 > bar 
+  $ hg ci -Am "commit on default"
+  adding bar
+
+Pull branchC from tt
+
+  $ hg pull ../tt
+  pulling from ../tt
+  searching for changes
+  adding changesets
+  adding manifests
+  adding file changes
+  added 1 changesets with 1 changes to 1 files (+1 heads)
+  (run 'hg heads' to see heads)