The bug
Snapshot 15w43b for 1.9 fixed MC-35790, an issue that made water hard to see through against glass due to it displaying the flowing texture. The fix made it display a flat, solid-colour texture instead. However, this also changed how glass looks from inside of the water - no texture is rendered against the glass at all. It'd be expected that the same flat water texture would be visible from inside the water, but this is not the case.
The inner top texture is correctly rendered against glass blocks (however it also renders some excess water textures incorrectly - see MC-175133). The inner bottom texture is not rendered in any circumstances at all, even though it should be - see MC-190053.
How to reproduce
Build a hollow stone cube with glass windows (example world provided)
View the windows from inside
Expected result
Translucent blue texture would be rendered on top of the glass.
Actual results
It is not.
Linked issues
testing discovered 1
Attachments
Comments 5
The flowing water shouldn't be rendered against the glass from within, but the flat texture introduced afterward should.
That'd just reintroduce the old bug in a different manner though, I'd consider the fact that it renders any water texture at all a bug, which is not the case currently. From my understanding, underwater glass is supposed to be see-through, or else underwater buildings using it would look weird again.
I don't quite understand what the bug here is. From my understanding the current behavior is that the water texture doesn't render at all against glass when looking from inside water, which was the fix for MC-35790. Are you asking for this to be reverted?
If what you believe should be expected is what the 15w43a image is despicting, to me it would be reintroducing the bug that was fixed long ago. I don't see why the texture would be rendered against glass if it's not the case against the stone.