sys.activate_stack_trampoline() perf_jit backend unreachable

[pablogsal]

The perf_jit backend option in sys.activate_stack_trampoline() cannot be activated due to a logic error in the backend selection code making calling sys.activate_stack_trampoline("perf_jit") not activate the perf JIT trampoline.

Linked PRs

• gh-141579: Fix perf_jit backend in sys.activate_stack_trampoline() #141580
• [3.14] gh-141579: Fix perf_jit backend in sys.activate_stack_trampoline() (GH-141580) #141581
• [3.13] gh-141579: Fix perf_jit backend in sys.activate_stack_trampoline() (GH-141580) #141582