Unable to use bone meal to make pumpkin/melon stems grow a melon

The bug

Bonemeal cannot be used on stems with age 7.

This doesn't happen before 1.13.

Based on the game code (20w07a, Mojang names) :
There is a piece of code in the function StemBlock.performBonemeal() specifies that when using bonemeal on stem with age 7 it will call the tick() function to try to grow a melon. However, the function isValidBonemealTarget() states that bone meal cannot be used when age is 7. They contradict each other, and I don't think the latter makes sense.