Comment 5 for bug 1814232

BTW it's instance a1.large, and the error message is a bit different:

 selftests: cpu-on-off-test.sh
 ========================================
 pid 19403's current affinity mask: 3
 pid 19403's new affinity mask: 1
 CPU online/offline summary:
 present_cpus = 0-1 present_max = 1
 Cpus in online state: 0-1
 Cpus in offline state: 0
 Limited scope test: one hotplug cpu
 (leaves cpu in the original state):
 online to offline to online: cpu 1
 ./cpu-on-off-test.sh: line 89: echo: write error: Input/output error
 online_cpu_expect_success 1: unexpected fail
 not ok 1..1 selftests: cpu-on-off-test.sh [FAIL]