Explained why in the updated commit message in http://git.altlinux.org/people/imz/packages/?p=mithraen-build-utils.git;a=commitdiff;h=2e77cfd3d17f5808c1f0ac1bacf0f504dac5c514 :

Cf. -- no 3rd argument is used:

$ girar-clone-build-commit -h
Usage:
    girar-clone-build-commit [-h] [-f] [-b *repository*] [-d *local
    destination branch*] [-n *local repository name*] [-o *name*] *name*
    [*local repository name*]

Options:
    -b *repository branch*
        Name of the repository branch. Values: sisyphus|5.1|p5|.. Default is
        sisyphus.

    -d *local destination branch name*
        Name of the checked out branch. Default is master.

    -f  Forcefully remove previous <name>.git and clone over even if
        <name>.git already exists.

    -h  Display this help and exit.

    -n *local repository name*
        Name of the local repository. Default is *name.git*. Can also be
        specified as the second argument.

    -o *remote name*
        Option passed to git-clone. Instead of using the remote name origin
        to keep track of the upstream repository, use *remote name*.

$

Just in case, not to loose and forget this minor clean-up tweak in the code:

task #153043

Please approve if that's OK with you when it is ready.

Task #153043 approved

mithraen-build-utils-0.1.27-alt2 -> sisyphus:

* Wed Nov 11 2015 Ivan Zakharyaschev <imz@altlinux> 0.1.27-alt2
- gear-clone: minor tweak (unneeded extra argument in the code removed)
  (ALT#31473).