uploader: Fix a bug while deleting.
uploader: Fix a bug while deleting.

Delete file if only it is referred from nowhere.

violetag/demo,naver/yobi,yona-projects/yona,ChangsungKim/TestRepository01,ihoneymon/yobi,violetag/demo,brainagenet/yobi,naver/yobi,ihoneymon/yobi,Limseunghwan/oss,doortts/fork-yobi,doortts/forked-for-history,bloodybear/yona,ahb0327/yobi,ihoneymon/yobi,doortts/fork-yobi,oolso/yobi,oolso/yobi,doortts/forked-for-history,ahb0327/yobi,bloodybear/yona,doortts/fork-yobi,brainagenet/yobi,doortts/fork-yobi,oolso/yobi,ChangsungKim/TestRepository01,bloodybear/yona,Limseunghwan/oss,brainagenet/yobi,Limseunghwan/oss,yona-projects/yona,yona-projects/yona,bloodybear/yona,doortts/forked-for-history,naver/yobi,yona-projects/yona,ahb0327/yobi