Commit 4c75f7c773 fixed a bug in which the TI-LFA repair paths
weren't preserving the original Prefix-SID of the routes. That
commit, however, didn't update the zebra interface code to account
for backup nexthops that don't have a repair list but do have a
SR label. As a consequence, backup nexthops that didn't have any
repair label were not preserving the original Prefix-SID of the
corresponding routes. Fix this and update the TI-LFA topotest
accordingly.
Signed-off-by: Renato Westphal <renato@opensourcerouting.org>
When computing backup nexthops for routes that contain a Prefix-SID,
the original Prefix-SID label should be present at the end of
backup label stacks (after the repair labels). This commit fixes
that oversight in the original TI-LFA code. The SPF unit tests and
TI-LFA topotes were also updated accordingly.
Signed-off-by: Renato Westphal <renato@opensourcerouting.org>