It's not just a bug with an associated patch. It's a language misfeature, in a 15 year old language. You can very probably fix it without breaking existing code.
And since a probable fix without breaking stuff is likely a patch would be all it takes (and a note in the changelog, for the unlikely case that someone did depend on it, not that they'll read the changelog ;) ).
Octal not being the popular thing it once was I doubt it would matter much.
I think more people are 'bitten' by this totally unexpected behaviour of leading 0's suddenly doing wildly interesting things to numbers (what?? there are more numberbases than just decimal???) than there are that expect illegal characters in octal numbers to throw errors.
