Made a-b -> a + -b count as a change; fixes a test
Made a-b -> a + -b count as a change; fixes a test

nemerle/boomerang,xujun10110/boomerang,TambourineReindeer/boomerang,TambourineReindeer/boomerang,nemerle/boomerang,TambourineReindeer/boomerang,xujun10110/boomerang,xujun10110/boomerang,nemerle/boomerang,xujun10110/boomerang,nemerle/boomerang,xujun10110/boomerang,nemerle/boomerang,nemerle/boomerang,xujun10110/boomerang,nemerle/boomerang,TambourineReindeer/boomerang,TambourineReindeer/boomerang,xujun10110/boomerang,xujun10110/boomerang,TambourineReindeer/boomerang,TambourineReindeer/boomerang,TambourineReindeer/boomerang,nemerle/boomerang