warning on push should mention heads, not branches

This makes the concept easier to relate to similar messages given on pull,
and allows for a distinction between heads and (named) branches.

mercurial/localrepo.py

@@ -1527,7 +1527,7 b' class localrepository(repo.repository):'
                     warn = 1
 
             if warn:
-                self.ui.warn(_("abort: push creates new remote branches!\n"))
+                self.ui.warn(_("abort: push creates new remote heads!\n"))
                 self.ui.status(_("(did you forget to merge?"
                                  " use push -f to force)\n"))
                 return None, 0

tests/test-push-warn.out

@@ -1,7 +1,7 b''
 1 files updated, 0 files merged, 0 files removed, 0 files unresolved
 pushing to ../a
 searching for changes
-abort: push creates new remote branches!
+abort: push creates new remote heads!
 (did you forget to merge? use push -f to force)
 pulling from ../a
 searching for changes
@@ -12,7 +12,7 b' added 1 changesets with 1 changes to 1 f'
 (run 'hg heads' to see heads, 'hg merge' to merge)
 pushing to ../a
 searching for changes
-abort: push creates new remote branches!
+abort: push creates new remote heads!
 (did you forget to merge? use push -f to force)
 1 files updated, 0 files merged, 0 files removed, 0 files unresolved
 (branch merge, don't forget to commit)
@@ -31,7 +31,7 b' 0 files updated, 1 files merged, 0 files'
 (branch merge, don't forget to commit)
 pushing to ../c
 searching for changes
-abort: push creates new remote branches!
+abort: push creates new remote heads!
 (did you forget to merge? use push -f to force)
 1
 pushing to ../c
@@ -40,12 +40,12 b' no changes found'
 0
 pushing to ../c
 searching for changes
-abort: push creates new remote branches!
+abort: push creates new remote heads!
 (did you forget to merge? use push -f to force)
 1
 pushing to ../c
 searching for changes
-abort: push creates new remote branches!
+abort: push creates new remote heads!
 (did you forget to merge? use push -f to force)
 1
 pushing to ../c