I see this copper pipe coming out of a stucco wall, crimped shut on the end.
I look on the other side of the wall and…
Bombity-Bomb
1/2" to boot…
Holy crap! Good catch.
It was an easy thing to spot. But I saw the exterior portion at first, and wondered if it could be the remnants of a water supply line (lots of evaporative coolers around here).
The crimped end was hidden behind some shrubs. It was installed incorrectly anyway, so it needed to be replaced.
But if the portion of the drain at the water heater looked good, it would be easy to not go poking around behind a thick hedge to find the end of the line.
This is a perfect example of why it is important to ALWAYS find and/or report on the termination point of the TPR drain.