Players can breathe while in flowing water

The bug

While working on a survival map, I went through a waterfall, and noticed I couldn't go to swimming mode in it (don't know if that bug has already been created) and i could breathe infinitelly whilst inside.

Steps to reproduce

1. Make a pillar from a block (or build a waterfall like I did)
2. Place a water bucket on top of it
3. Go inside of the flowing water

Note

While attempting to recreate this bug, I noticed removing the top water source in the last picture, both water source blocks were removed.