Generated main/debug/<arch>/Packages.xz/gz files are empty

[Mina Galić]

According to the documentation: https://wiki.ubuntu.com/DebuggingProgramCrash#Installing_dbgsym_packages_from_a_PPA in order to enable a repository's debug symbols section, I have to add main/debug.

I did so for many, many repos, but here's the result for Firefox:

```
deb http://ppa.launchpad.net/mozillateam/firefox-next/ubuntu bionic main main/debug
deb-src http://ppa.launchpad.net/mozillateam/firefox-next/ubuntu bionic main
```

then we run apt update with the following result:

All packages are up to date.
W: Skipping acquire of configured file 'main/debug/i18n/Translation-en' as repository 'http://ppa.launchpad.net/mozillateam/firefox-next/ubuntu bionic InRelease' doesn't have the component 'main/debug' (component misspelt in sources.list?)
W: Skipping acquire of configured file 'main/debug/i18n/Translation-en_US' as repository 'http://ppa.launchpad.net/mozillateam/firefox-next/ubuntu bionic InRelease' doesn't have the component 'main/debug' (component misspelt in sources.list?)
W: Skipping acquire of configured file 'main/debug/dep11/Components-amd64.yml' as repository 'http://ppa.launchpad.net/mozillateam/firefox-next/ubuntu bionic InRelease' doesn't have the component 'main/debug' (component misspelt in sources.list?)
W: Skipping acquire of configured file 'main/debug/Contents-i386' as repository 'http://ppa.launchpad.net/mozillateam/firefox-next/ubuntu bionic InRelease' doesn't have the component 'main/debug' (component misspelt in sources.list?)
W: Skipping acquire of configured file 'main/debug/Contents-amd64' as repository 'http://ppa.launchpad.net/mozillateam/firefox-next/ubuntu bionic InRelease' doesn't have the component 'main/debug' (component misspelt in sources.list?)
W: Skipping acquire of configured file 'main/debug/cnf/Commands-amd64' as repository 'http://ppa.launchpad.net/mozillateam/firefox-next/ubuntu bionic InRelease' doesn't have the component 'main/debug' (component misspelt in sources.list?)

We get the warnings for all these missing files, but we don't get a warning that the downloaded Packages.xz is empty!

So even tho the -dbgsym package exists: http://ppa.launchpad.net/mozillateam/firefox-next/ubuntu/pool/main/f/firefox/
it's not referenced anywhere and so cannot be installed.

[Jan Wielemaker (jan-swi-prolog)]

Same problem for `deb http://ppa.launchpad.net/swi-prolog/devel/ubuntu bionic main main/debug`

[Trent Lloyd (lathiat)]

The reason for this is that debug symbol packages are not generated by default.

The owner of the PPA needs to enable them after creating the PPA (and before upload) by navigating to the PPA, selecting "Change Details" and then ticking the "Build debug symbols" and "Publish debug symbols" options which are not on by default.