What do you expect to happen? To the extent that the battery is compromised, the water is mostly going to make it short to itself, and it isn't as if a raging battery fire is going to be a better situation for the apparently trapped occupant (the only time the immediate car environment is particularly troublesome).
(The linked manual specifies using water to cool the battery and discusses observation procedures to limit the risk of re-ignition...)
At one extreme, nothing. At the other, a potentially horrible electrocution. Run a google image search for something like "serious car accident" and insert an equally mangled battery pack in there. I very much doubt Tesla or any other electric car manufacturer would even remotely consider issuing a blanket guarantee stating that their design is electrocution-proof under all conditions.
Not trying to be a troll. Simply saying that high voltage systems are extremely dangerous. That's it. No need to agree with me. Just remember I said it.
It would be nuts if the interconnects have higher survivability than the firewalls. Mangling the battery will almost certainly significantly reduce the voltage (I didn't quickly find anything on the Model S, but for the Roadster, the output voltage is achieved with a final series arrangement of sub-assemblies, breaking that should directly reduce voltage).
Of course it will still create dangerous situations and experience will be valuable in judging just how dangerous.
(The linked manual specifies using water to cool the battery and discusses observation procedures to limit the risk of re-ignition...)