Change dir test deletes to a variable.
Change dir test deletes to a variable.

The dir that updates in set_update_create_test.go's TestCreateInOrder
function are posted to is already put into a variable, so change the
defer to use that variable to ensure the dir is deleted at the end of
the test.

coreos/go-etcd,Yhgenomics/go-etcd,shafreeck/go-etcd,mbrukman/go-etcd,kmchen/go-etcd,zenoss/go-etcd,mischief/go-etcd,stormltf/go-etcd,nordligulv/go-etcd,giantswarm/go-etcd,barakmich/go-etcd,pquerna/go-etcd,pengzj/go-etcd,wangyumi/go-etcd