Improve MergeRequest#head_pipeline
Improve MergeRequest#head_pipeline

jirutka/gitlabhq,dreampet/gitlab,dreampet/gitlab,mmkassem/gitlabhq,iiet/iiet-git,axilleas/gitlabhq,stoplightio/gitlabhq,dreampet/gitlab,iiet/iiet-git,stoplightio/gitlabhq,jirutka/gitlabhq,mmkassem/gitlabhq,mmkassem/gitlabhq,iiet/iiet-git,iiet/iiet-git,axilleas/gitlabhq,dreampet/gitlab,stoplightio/gitlabhq,jirutka/gitlabhq,stoplightio/gitlabhq,jirutka/gitlabhq,mmkassem/gitlabhq,axilleas/gitlabhq,axilleas/gitlabhq