IKEv2 RW with subnets, using auto=start

On libreswan 4.4 and earlier, this failed with:

|    match_id a=C=CA, ST=Ontario, L=Toronto, O=Libreswan, OU=Test Department, CN=road.testing.libreswan.org, E=user-road@testing.libreswan.org
|             b=%fromcert
|    results  fail
|     connection "east/0x2" does not match IDs or CA of current connection "east/0x1"

Clearly, this is wrong, as both connections are instantiated and are identical in IKE SA params.
In libreswan 4.5, the code verifies that both are derived as aliases from the same base conn.
