public function testGetHeadCommits()
 {
     $instance = new VersionControl_Git('./fixtures/001_VersionControl_Git');
     $heads = $instance->getHeadCommits();
     $this->assertEquals($heads['master'], '4ed54abb8efca38a0c794ca414b1f296279e0d85');
     $this->assertEquals($heads['branch1'], '373efdec06a5847fd279d8c442dbfdd5df41e783');
 }