Mark placeholder "<branch>" in git-rebase.sh for translation. The string
containing the named placeholder is passed to shell function
error_on_missing_default_upstream in git-parse-remote.sh which uses it
to display a command hint for the user.
Signed-off-by: Vasco Almeida <vascomalmeida@sapo.pt> Signed-off-by: Junio C Hamano <gitster@pobox.com>