Ring of sustain ability can be used to exploit strength mod when becoming (un)weak from hunger

[tung]

These steps will raise strength by 1 permanently each time they're done:

1. Put on ring of sustain ability.
2. Become weak from hunger.
3. Remove ring of sustain ability.
4. Eat something (e.g. meatball) to go from weak -> hungry.

From #unnethack on FreeNode:

I discovered something today that I think should be fixed: ring of sustain ability.
it can be used to exploit hunger for max str
put on ring while hungry, wait for weak, str doesn't go down, remove ring, eat a meatball, str goes up. repeat.
it seems like if you are weak from hunger, removing the ring while weak should immediately apply the -1 str