This allows supported_arches to be configured, which should be used by
our directives (like koji) to decide which architectures to act upon
(e.g. which binary RPMs to download). This option defaults to primary
Fedora architectures.
Koji calls had a special parameter arches=['all'] which used to
download all available RPMs. It now downloads all available *supported*
RPMs (per config.supported_arches). This allows dynamic configuration
on a server to handle only specific architectures (or extend handling
beyond just primary ones). Tasks can still download "non-supported"
architectures if they list them explictly.
This patch was triggered by redefining how secondary (now alternate)
architectures are handled in Fedora. All alternate arches will now be
built and served from the primary Koji instance, thus the need to adjust
this in libtaskotron. Read more at: