PullRequest: Fix server error when conflict occurs
PullRequest: Fix server error when conflict occurs

Reason: NPE occurred when a merge conflicts because Yobi tries to get
the number of the merged commits even if the list is null.

Solution: Set the list of commits Yobi tries to merge even if the merge
conflicts.

yona-projects/yona,ihoneymon/yobi,bloodybear/yona,doortts/forked-for-history,naver/yobi,naver/yobi,bloodybear/yona,doortts/forked-for-history,doortts/fork-yobi,Limseunghwan/oss,doortts/fork-yobi,yona-projects/yona,yona-projects/yona,ihoneymon/yobi,oolso/yobi,doortts/fork-yobi,doortts/fork-yobi,brainagenet/yobi,oolso/yobi,brainagenet/yobi,ihoneymon/yobi,bloodybear/yona,ahb0327/yobi,yona-projects/yona,naver/yobi,Limseunghwan/oss,ahb0327/yobi,ahb0327/yobi,brainagenet/yobi,Limseunghwan/oss,doortts/forked-for-history,oolso/yobi,bloodybear/yona