Full write-up here: http://blog.adamcameron.me/2015/05/cfml-lucee-beware-of-optional-semi.html
I'd not normally report this sort of thing separately, but on Lucee 5 the code doesn't break, it just doesn't work properly. The abort gets ignored. On 4.5 it errors-out like one comes to expect when using "optional" semi-colons where they're not actually optional.
Also note this ties-in with too, which is a staging area of various circumstances where optional semi-colons aren't (~ optional).