Description of problem:
dnf update is now downloading packages in parallel.
but dnf makecache is also pretty slow
(depending on a network), making it fetch
cache from unrelated repos in parallel would
speed this up.

Version-Release number of selected component (if applicable):
dnf-1.1.2-4.fc22.noarch

How reproducible:
always

Steps to Reproduce:
1. run as root:
# time dnf makecache
2. compare time reported for each repo and total real time

Actual results:
each repo is updated separately, one after another,
total time is the sum of times for each repo

Expected results:
Total time is worst time for a repo.

Additional info:
Can some downloads be parallelized within repo?
Might be worth considering, but might increase load on repo servers.