portfile main block requires master_sites key

[jpm@…]

the main block of a portfile requires the master_sites key to be defined even if it is overwritten in the variants. this causes 'port fetch' to fail but gets past 'portindex'. this is an issue for portfiles that only define variants and do not define a port in main - in the interim, you can set master_sites to any value in main knowning it will be overwritten later

[landonf@…]

The main block of a port must ALWAYS be a valid port, and default_variants should never be depended upon to fill in valid data. If a port varies so much that there can not be a 'base' version and a number of variants on that base, it suggests that there ought to be multiple ports.