translations: change label integer error to not specify the kind of label
The current error message used the kind (bookmark, branch, tag) in the message.
Unfortunately this isn't easily translatable since some languages give different
genders to these words. The fix is to not specify it at all, since it should be
implicit based on the command the user just ran.
Relevant discussions around this area:
http://selenic.com/pipermail/mercurial-devel/2012-October/045567.html
http://selenic.com/pipermail/mercurial-devel/2012-October/045600.html