6ln RA PIO with L flag set is not ignored #20377
Description
Description
(This was noticed because of the tests failing in #20371 )
A router MUST NOT set the L (on-link) flag in the PIOs, since that
might trigger hosts to send multicast NSs.
Should the host erroneously receive a PIO with the L (on-link) flag
set, then that PIO MUST be ignored.
The latter quote is not implemented in either tests or tested code.
Code implementation (tested code) adjustment would be a new PIO validity check failure condition: || (gnrc_netif_is_6ln(netif) && (pio->flags & NDP_OPT_PI_FLAGS_L))
Test adjustment is slightly more changes.
Steps to reproduce the issue
For example, observe failing tests in #20371
Expected results
These tests that currently fail in #20371 should not do so.
Actual results
They do fail.
Versions
Murdock on #20371