[backend] support caching of an repodata error state
[backend] add arch parameter to addrepo_remote
[backend] bugfix: make sure addrepo_alien does not mess with %prpnotready
[backend] refactor: split update_projpacks from get_projpacks
[backend] update remote project data with data from remotemap to reduce RPCs
[backend] fix comment
[backend] refactor: split clone_projpacks_part and postprocess_needed_check from delayedfetchprojpacks processing
[backend] refactor: split find_linked_sources from do_fetchprojpacks
[backend] report network errors in getprojpack as "interconnect errors"
[backend] first try of async scheduler, enable with $BSConfig::sched_asyncmode = 1