FreeBSD-main-amd64-test - Build #21839 - Still Unstable

FreeBSD-main-amd64-test - Build #21839 (9d16275c65bfe0f577e6f97397e024a33169acc9) - Still Unstable

Build information: https://ci.FreeBSD.org/job/FreeBSD-main-amd64-test/21839/
Full change log: https://ci.FreeBSD.org/job/FreeBSD-main-amd64-test/21839/changes
Full build log: https://ci.FreeBSD.org/job/FreeBSD-main-amd64-test/21839/console

Status explanation:
"Unstable" - some tests are suspected being broken by the following changes
"Still Unstable" - the failing test cases have not been fixed by these
                   following changes and this is a notification to note that
                   these changes have not been fully tested by the CI system

Change summaries:
(Those commits are likely but not certainly responsible)

9d16275c65bfe0f577e6f97397e024a33169acc9 by melifaro:
netinet6: simplify defrouter_select_fib()



The failed test cases:

1 tests failed.
FAILED:  lib.libc.locale.c16rtomb_test.c16rtomb_utf_8_test

Error Message:
/usr/src/lib/libc/tests/locale/c16rtomb_test.c:145: c16rtomb(buf, L'A', &s) == (size_t)-1 not met