Instead of just skipping interfaces that are "up", skip the whole
repeated_updown test case unless explicitly enabled with "atf-run -v
run_unsafe=yes". Gratuitously configuring interfaces "up" is no more
safe than gratuitously configuring them "down"; for example, it could
lead to accidentally connecting to an insecure network or diverting
traffic from the desired route.

Skip interfaces that are already UP before the test starts. We can
not change state of the test host this way, it breaks e.g. test systems
with the root filesystem on NFS.

Use atf_pass to avoid test failure in case there are no suitable interfaces.

Reference also PR kern/52526.

Add a test case for kern/52771.

Skip interfaces that are already UP before the test starts. We can
not change state of the test host this way, it breaks e.g. test systems
with the root filesystem on NFS.

Use atf_pass to avoid test failure in case there are no suitable interfaces.

Reference also PR kern/52526.

Add a test case for kern/52771.

Use atf_pass to avoid test failure in case there are no suitable interfaces.

Reference also PR kern/52526.

Add a test case for kern/52771.