What that point says is that it is a bug, but that a decision was made not to fix it for specific identifiers in order not to break some scripts which were poorly coded.

I can understand this decision as a short-term expediency, however IMO it would have been better to deprecate it in 5.7, issue warnings in 6.x and fix it in 7.x.

Or even perhaps to deprecate it in 5.7, to auto-fix the code in 6.x and revert to correct behaviour in 7.x.