This test can fail due to a fix in musl for 32 bit MIPS, where musl changes limits greater than -1UL/2 to RLIM_INFINITY.
See http://git.musl-libc.org/cgit/musl/commit/src/misc/getrlimit.c?id=8258014fd1e34e942a549c88c7e022a00445c352

Depending on the system where the test is run getrlimit can return
RLIM_INFINITY for example if RLIMIT_MEMLOCK is bigger than ~2GiB.

If that happens, the setrlimit call will fail with PermissionDenied.