1 from __future__ import absolute_import

     2 

     3 from mercurial import (

     4     error,

     5     node,

     6 )

     7 

     8 from mercurial.i18n import _

     9 

    10 def enforcesinglehead(repo, tr):

    11     for name, heads in repo.filtered('visible').branchmap().iteritems():

    12         if len(heads) > 1:

    13             hexs = [node.short(n) for n in heads]

    14             raise error.Abort(_('%d heads on "%s"') % (len(heads), name),

    15                               hint=(', '.join(hexs)))