make expected due_date value format explicit
make expected due_date value format explicit

darkrasid/gitlabhq,dplarson/gitlabhq,LUMC/gitlabhq,mmkassem/gitlabhq,dplarson/gitlabhq,t-zuehlsdorff/gitlabhq,dreampet/gitlab,stoplightio/gitlabhq,htve/GitlabForChinese,stoplightio/gitlabhq,LUMC/gitlabhq,htve/GitlabForChinese,htve/GitlabForChinese,openwide-java/gitlabhq,stoplightio/gitlabhq,LUMC/gitlabhq,mmkassem/gitlabhq,dplarson/gitlabhq,mmkassem/gitlabhq,dreampet/gitlab,htve/GitlabForChinese,axilleas/gitlabhq,t-zuehlsdorff/gitlabhq,jirutka/gitlabhq,dplarson/gitlabhq,dreampet/gitlab,darkrasid/gitlabhq,iiet/iiet-git,iiet/iiet-git,t-zuehlsdorff/gitlabhq,mmkassem/gitlabhq,darkrasid/gitlabhq,iiet/iiet-git,t-zuehlsdorff/gitlabhq,dreampet/gitlab,jirutka/gitlabhq,iiet/iiet-git,openwide-java/gitlabhq,openwide-java/gitlabhq,darkrasid/gitlabhq,axilleas/gitlabhq,jirutka/gitlabhq,LUMC/gitlabhq,axilleas/gitlabhq,axilleas/gitlabhq,jirutka/gitlabhq,stoplightio/gitlabhq,openwide-java/gitlabhq