CI tests failing

[fingolfin]

Some time ago the CI tests started failing, with errors like this (different in older GAP versions):

Panic in src/sysfiles.c:173: Could not write to stdout: Input/output error (errno 5, fid 0)

[RussWoodroofe]

Was there any configuration change around when it started to fail? Does it consistently fail, or sometimes fail? I note that xgap_test.g makes significant use of streams -- it opens a child GAP process with the equivalent of "gap - p", and processes input/output for that process. Is it possible that there's some kind of race condition in GAP streams?

Looking at the following two
https://github.com/gap-packages/xgap/runs/8275015520?check_suite_focus=true
https://github.com/gap-packages/xgap/runs/8275015726?check_suite_focus=true
It looks to me like it sometimes fails, but doesn't always. I notice a difference in how the input is getting fed, although that shouldn't make a difference.