As we are now only processing ~7k tasks per run, I'm not too worried by
its slowness.

Before it would only match if "download attachment" was true and it
would also match other <a> with "https://bugs.archlinux.org".

ALBS_PARALLELIZE_DOWNLOAD=true to enable

It doesn't seem to improve performance just load on bugs.al.org.

One single prettify can use the full CPU core, so there is no reason to
spawn 50 of them.

Fixes: "fatal: 'public' is a missing but already registered worktree;"

It is slow, very slow (~300-400ms per file).

If a task doesn't exist the server returns 302 which wget interprets as
a error due to --max-redirect 0.