Ignore core.db.sig and extra.db.sig download errors

[balki]

I think it safe to assume the behavior is not expected to change anytime soon since it has not changed for decades.

1. Avoids unnecessary pings to all configured mirror servers
2. Removes the noise from logs

fixes #112

[anatol]

Thank you! The fix looks good to me.

[adrfantini]

Is this why pacoloco is giving me this many 404 errors and is very slow at retrieving DBs? (see below)

Also, to me it seems a bit weird that the fix is that it tries to download the .sig and just ignores the error, instead of skipping the download altogether.

pacoloco   | downloader.go:116: downloading https://de.arch.niranjan.co//core/os/x86_64/core.db
pacoloco   | pacoloco.go:273: serving cached file for archlinux-reflector/core/os/x86_64/core.db
pacoloco   | downloader.go:116: downloading https://de.arch.niranjan.co//core/os/x86_64/core.db.sig
pacoloco   | downloader.go:82: unable to download file archlinux-reflector/core/os/x86_64/core.db.sig: unable to download url https://de.arch.niranjan.co//core/os/x86_64/core.db.sig, status code is 404
pacoloco   | downloader.go:116: downloading https://mirror.moson.org/arch//core/os/x86_64/core.db.sig
pacoloco   | downloader.go:82: unable to download file archlinux-reflector/core/os/x86_64/core.db.sig: unable to download url https://mirror.moson.org/arch//core/os/x86_64/core.db.sig, status code is 404
pacoloco   | downloader.go:116: downloading https://mirror.lcarilla.de/archlinux//core/os/x86_64/core.db.sig
pacoloco   | downloader.go:82: unable to download file archlinux-reflector/core/os/x86_64/core.db.sig: unable to download url https://mirror.lcarilla.de/archlinux//core/os/x86_64/core.db.sig, status code is 404
pacoloco   | downloader.go:116: downloading https://arch.phinau.de//core/os/x86_64/core.db.sig
pacoloco   | downloader.go:82: unable to download file archlinux-reflector/core/os/x86_64/core.db.sig: unable to download url https://arch.phinau.de//core/os/x86_64/core.db.sig, status code is 404
pacoloco   | downloader.go:116: downloading https://archlinux.thaller.ws//core/os/x86_64/core.db.sig
pacoloco   | downloader.go:82: unable to download file archlinux-reflector/core/os/x86_64/core.db.sig: unable to download url https://archlinux.thaller.ws//core/os/x86_64/core.db.sig, status code is 404
pacoloco   | downloader.go:116: downloading https://arch.jensgutermuth.de//core/os/x86_64/core.db.sig
pacoloco   | downloader.go:82: unable to download file archlinux-reflector/core/os/x86_64/core.db.sig: unable to download url https://arch.jensgutermuth.de//core/os/x86_64/core.db.sig, status code is 404
pacoloco   | downloader.go:116: downloading https://at.arch.mirror.kescher.at//core/os/x86_64/core.db.sig
pacoloco   | downloader.go:82: unable to download file archlinux-reflector/core/os/x86_64/core.db.sig: unable to download url https://at.arch.mirror.kescher.at//core/os/x86_64/core.db.sig, status code is 404
pacoloco   | downloader.go:116: downloading https://mirror.ubrco.de/archlinux//core/os/x86_64/core.db.sig
pacoloco   | downloader.go:82: unable to download file archlinux-reflector/core/os/x86_64/core.db.sig: unable to download url https://mirror.ubrco.de/archlinux//core/os/x86_64/core.db.sig, status code is 404
pacoloco   | downloader.go:116: downloading https://archlinux.mailtunnel.eu//core/os/x86_64/core.db.sig
pacoloco   | downloader.go:82: unable to download file archlinux-reflector/core/os/x86_64/core.db.sig: unable to download url https://archlinux.mailtunnel.eu//core/os/x86_64/core.db.sig, status code is 404
pacoloco   | downloader.go:116: downloading https://mirror.cyberbits.eu/archlinux//core/os/x86_64/core.db.sig
pacoloco   | downloader.go:116: downloading https://de.arch.niranjan.co//extra/os/x86_64/extra.db
pacoloco   | downloader.go:116: downloading https://de.arch.niranjan.co//extra/os/x86_64/extra.db.sig
pacoloco   | downloader.go:82: unable to download file archlinux-reflector/extra/os/x86_64/extra.db.sig: unable to download url https://de.arch.niranjan.co//extra/os/x86_64/extra.db.sig, status code is 404
pacoloco   | downloader.go:116: downloading https://mirror.moson.org/arch//extra/os/x86_64/extra.db.sig
pacoloco   | downloader.go:82: unable to download file archlinux-reflector/extra/os/x86_64/extra.db.sig: unable to download url https://mirror.moson.org/arch//extra/os/x86_64/extra.db.sig, status code is 404
pacoloco   | downloader.go:116: downloading https://mirror.lcarilla.de/archlinux//extra/os/x86_64/extra.db.sig
pacoloco   | downloader.go:82: unable to download file archlinux-reflector/extra/os/x86_64/extra.db.sig: unable to download url https://mirror.lcarilla.de/archlinux//extra/os/x86_64/extra.db.sig, status code is 404
pacoloco   | downloader.go:116: downloading https://arch.phinau.de//extra/os/x86_64/extra.db.sig
pacoloco   | downloader.go:82: unable to download file archlinux-reflector/extra/os/x86_64/extra.db.sig: unable to download url https://arch.phinau.de//extra/os/x86_64/extra.db.sig, status code is 404
pacoloco   | downloader.go:116: downloading https://archlinux.thaller.ws//extra/os/x86_64/extra.db.sig
pacoloco   | downloader.go:82: unable to download file archlinux-reflector/core/os/x86_64/core.db.sig: unable to download url https://mirror.cyberbits.eu/archlinux//core/os/x86_64/core.db.sig, status code is 404
pacoloco   | downloader.go:365: unable to download file archlinux-reflector/core/os/x86_64/core.db.sig
pacoloco   | pacoloco.go:168: unable to download file archlinux-reflector/core/os/x86_64/core.db.sig
pacoloco   | downloader.go:82: unable to download file archlinux-reflector/extra/os/x86_64/extra.db.sig: unable to download url https://archlinux.thaller.ws//extra/os/x86_64/extra.db.sig, status code is 404
pacoloco   | downloader.go:116: downloading https://arch.jensgutermuth.de//extra/os/x86_64/extra.db.sig
pacoloco   | downloader.go:82: unable to download file archlinux-reflector/extra/os/x86_64/extra.db.sig: unable to download url https://arch.jensgutermuth.de//extra/os/x86_64/extra.db.sig, status code is 404
pacoloco   | downloader.go:116: downloading https://at.arch.mirror.kescher.at//extra/os/x86_64/extra.db.sig
pacoloco   | downloader.go:82: unable to download file archlinux-reflector/extra/os/x86_64/extra.db.sig: unable to download url https://at.arch.mirror.kescher.at//extra/os/x86_64/extra.db.sig, status code is 404
pacoloco   | downloader.go:116: downloading https://mirror.ubrco.de/archlinux//extra/os/x86_64/extra.db.sig
pacoloco   | downloader.go:82: unable to download file archlinux-reflector/extra/os/x86_64/extra.db.sig: unable to download url https://mirror.ubrco.de/archlinux//extra/os/x86_64/extra.db.sig, status code is 404
pacoloco   | downloader.go:116: downloading https://archlinux.mailtunnel.eu//extra/os/x86_64/extra.db.sig
pacoloco   | downloader.go:82: unable to download file archlinux-reflector/extra/os/x86_64/extra.db.sig: unable to download url https://archlinux.mailtunnel.eu//extra/os/x86_64/extra.db.sig, status code is 404
pacoloco   | downloader.go:116: downloading https://mirror.cyberbits.eu/archlinux//extra/os/x86_64/extra.db.sig
pacoloco   | downloader.go:82: unable to download file archlinux-reflector/extra/os/x86_64/extra.db.sig: unable to download url https://mirror.cyberbits.eu/archlinux//extra/os/x86_64/extra.db.sig, status code is 404
pacoloco   | downloader.go:365: unable to download file archlinux-reflector/extra/os/x86_64/extra.db.sig
pacoloco   | pacoloco.go:168: unable to download file archlinux-reflector/extra/os/x86_64/extra.db.sig
pacoloco   | downloader.go:116: downloading https://de.arch.niranjan.co//community/os/x86_64/community.db
pacoloco   | pacoloco.go:273: serving cached file for archlinux-reflector/community/os/x86_64/community.db
pacoloco   | downloader.go:116: downloading https://de.arch.niranjan.co//community/os/x86_64/community.db.sig
pacoloco   | downloader.go:82: unable to download file archlinux-reflector/community/os/x86_64/community.db.sig: unable to download url https://de.arch.niranjan.co//community/os/x86_64/community.db.sig, status code is 404
pacoloco   | downloader.go:116: downloading https://mirror.moson.org/arch//community/os/x86_64/community.db.sig
pacoloco   | downloader.go:82: unable to download file archlinux-reflector/community/os/x86_64/community.db.sig: unable to download url https://mirror.moson.org/arch//community/os/x86_64/community.db.sig, status code is 404
pacoloco   | downloader.go:116: downloading https://mirror.lcarilla.de/archlinux//community/os/x86_64/community.db.sig
pacoloco   | downloader.go:82: unable to download file archlinux-reflector/community/os/x86_64/community.db.sig: unable to download url https://mirror.lcarilla.de/archlinux//community/os/x86_64/community.db.sig, status code is 404
pacoloco   | downloader.go:116: downloading https://arch.phinau.de//community/os/x86_64/community.db.sig

To future people like me: a good solution is to use CacheServer instead of Server in your pacman.conf!
#104