Multi-valued RDN in Subject Alternative Name extension

["Williams, Gareth" <gareth@xxxxxxxxxxxxxxxxxxxx>]

I can successfully add a multi-value RDN to the Subject of a
certificate request using the + format in the config file:

    distinguished_name = req_dn

    [ req_dn ]
    O=Acme
    CN=Bloggs
    +C=GB

However, if I add a SAN to the request:

    subjectAltName = @alt_names

    [ alt_names ]
    DNS = www.example.com
    dirName = req_dn

the resulting request has them as separate RDNs (as if the + is not noticed).

That is, the resulting subject field is: O = Acme, C = GB + CN = Test
While the resulting SAN extension is: DNS:www.example.com,
DirName:/O=Acme/C=GB/CN=Test

Should multi-value RDNs work in the SAN too?

Kind regards,

Gareth Williams