Shallow clone with one commit that corresponds to arbitrary tag from arbitrary branch

I try to clone a single revision from arbitrary branch. Something like:

    git clone --depth 1 --branch v2.6.1 https://github.com/symfony/symfony-standard.git

Here: v2.6.1 is a tag. And I want to clone only one revision: the one that corresponds to this tag.

The following configuration:

    vcsrepo { '/home/vagrant/p01':
      provider => 'git',
      source   => 'https://github.com/symfony/symfony-standard.git',
      user     => 'vagrant',
      revision => 'v2.6.1',
      depth    => 1
    }

fails producing the error:

    Error: Execution of '/bin/su vagrant -c git checkout --force v2.6.1' returned 1:
    error: pathspec 'v2.6.1' did not    match any file(s) known to git.

I think `branch` parameter is necessary.

I have already made one PR: #212

This time I removed superfluous parameter `--single-branch`.

What do you think @sodabrew?