Fix merge request diff create and head_commit_sha compatibility
Fix merge request diff create and head_commit_sha compatibility

Signed-off-by: Dmitriy Zaporozhets <be23d75b156792e5acab51b196a2deb155d35d6a@gmail.com>

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