svn sync over https broken with new HOME

[Joshua Root]

'port sync' now fails for me with
https://svn.macports.org/repository/macports/trunk/dports in
sources.conf. Error is "Server certificate verification failed: issuer
is not trusted".

It seems that the subversion port doesn't know about the Apple-supplied
root certs, and it's really inconvenient to put a config file in
/opt/local/var/macports/home. /usr/bin/svn might do better.

- Josh