Split try_merge_period into overlap? and merge:
Split try_merge_period into overlap? and merge:

Feedback:
https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/6084#note_15083507

t-zuehlsdorff/gitlabhq,shinexiao/gitlabhq,SVArago/gitlabhq,axilleas/gitlabhq,daiyu/gitlab-zh,shinexiao/gitlabhq,openwide-java/gitlabhq,dplarson/gitlabhq,htve/GitlabForChinese,screenpages/gitlabhq,htve/GitlabForChinese,dreampet/gitlab,t-zuehlsdorff/gitlabhq,jirutka/gitlabhq,axilleas/gitlabhq,jirutka/gitlabhq,openwide-java/gitlabhq,SVArago/gitlabhq,mmkassem/gitlabhq,htve/GitlabForChinese,jirutka/gitlabhq,daiyu/gitlab-zh,LUMC/gitlabhq,LUMC/gitlabhq,iiet/iiet-git,icedwater/gitlabhq,axilleas/gitlabhq,SVArago/gitlabhq,iiet/iiet-git,darkrasid/gitlabhq,daiyu/gitlab-zh,shinexiao/gitlabhq,iiet/iiet-git,allysonbarros/gitlabhq,jirutka/gitlabhq,stoplightio/gitlabhq,darkrasid/gitlabhq,stoplightio/gitlabhq,dreampet/gitlab,allysonbarros/gitlabhq,t-zuehlsdorff/gitlabhq,icedwater/gitlabhq,screenpages/gitlabhq,mmkassem/gitlabhq,screenpages/gitlabhq,icedwater/gitlabhq,dreampet/gitlab,dplarson/gitlabhq,iiet/iiet-git,shinexiao/gitlabhq,LUMC/gitlabhq,htve/GitlabForChinese,t-zuehlsdorff/gitlabhq,stoplightio/gitlabhq,dplarson/gitlabhq,mmkassem/gitlabhq,LUMC/gitlabhq,SVArago/gitlabhq,darkrasid/gitlabhq,axilleas/gitlabhq,darkrasid/gitlabhq,openwide-java/gitlabhq,stoplightio/gitlabhq,openwide-java/gitlabhq,screenpages/gitlabhq,icedwater/gitlabhq,allysonbarros/gitlabhq,dplarson/gitlabhq,allysonbarros/gitlabhq,mmkassem/gitlabhq,dreampet/gitlab,daiyu/gitlab-zh