gather changelogs in parallel
Before:
13.88user 4.18system 0:18.09elapsed 99%CPU (0avgtext+0avgdata 16712maxresident)k
0inputs+0outputs (0major+1357532minor)pagefaults 0swaps
After:
24.18user 5.63system 0:04.23elapsed 704%CPU (0avgtext+0avgdata 16760maxresident)k
8inputs+0outputs (0major+1365730minor)pagefaults 0swaps
Signed-off-by: Igor Gnatenko <ignatenkobrain@fedoraproject.org>