Yeah, about that...
I know this only started happening in 1.1.17, but I included 1.1.15 for good measure. I'd like to point out how nowhere in there does it explain why plain old vanilla bottled water won't fill up my thirst bar. The closest it comes to is the Enviromine update, and that doesn't explain anything, and as someone who's used packs with Enviromine before, it seems a touch illogical that the mod that requires you to drink or die would remove regular, clean water as a hydration source (and still leave it drinkable!) while forcing people to craft and drink either dirty or salt water (which are bad for you) or cold water (which one would be hard pressed to craft after spawning in a vanilla world before dying of starvation, if I remember the recipe correctly).
So unless either Enviromine decided to screw virtually everyone over or I'm just missing things on my third reread of the most recent changelogs, there's nothing in them about why bottle water no longer restores thirst like it used to.
The only other thing I can fathom you misconstruing for anything similar to an explanation is the overhaul of the water PRODUCTION (from 1.1.17), which is, by all appearances, a change in how one might procure water, but does not indicate in any way why drinking it no longer works. In fact, that it mentions producing water at all implies that water can still be drunk, and by no great leap of logic, one might assume that that would include water placed in a bottle.
So in short, unless I'm ridiculously blind, there's absolutely nothing in the changelogs about why water bottles can no longer be drank (drunk?) to regain thirst, or anything that would logically lead to that conclusion.
EDIT: In fact, your changelog implies that bottles still work:
- Overhauled water production, snow cooking now has only 1 cooking tick now, but produces less water, Mashed leaves has 4 cooking ticks now but makes 8 bottles!
but makes 8 bottles!
Yeah. 1.1.17, where water bottles can not be drank for hydration, you point out how mashed leaves make 8 bottles of water. I honestly can't fathom how you could suggest that that in any way implies, much less explains that water bottles no longer work to fill the thirst bar. (I'd quote, but it won't do it for me through editing. See above to see where I got these from)