Consider Dxx that was created against commit 'aa1zz255' that you don't have in your local repository. When you do arc patch Dxx, arc will tell you that the commit doesn't exist. If you abort the branch arcpatch-Dxx is not removed. The best alternative for this case IMO is to ask you if you want to pull the base branch. But in all case if you abort an arc command, arc should do the clean.

Tested against 4d4d16f25985f133501f20fdddd183e525f00341