With this patch, Pungi can be configured with a local directory to be
used as a cache for RPMs, and it will download packages from Koji over
HTTP instead of reading them from filesystem directly.
The files from the cache can then be hardlink as usual.
There is locking in place to avoid different composes running at the
same time to step on each other.
This is now supported for RPMs only, be it real builds or scratch
builds.
Signed-off-by: Lubomír Sedlář <lsedlar@redhat.com>
(cherry picked from commit 631bb01d8f)
