Further debugging info:
* run `apt install --reinstall` against each of the broken build
dependencies
* run `apt install ruby-dev`
* run `gem pristine --all`
This gets rid of the first few the errors, but bumps up against a
different error when trying to rebuild the `ruby-ffi` gem:
ERROR: While executing gem ... (Gem::Package::FormatError)
No such file or directory @ rb_sysopen -
/usr/lib/x86_64-linux-gnu/rubygems-integration/3.3.0/cache/ffi-1.17.0.gem
root@fum:/etc/schleuder# ls
/usr/lib/x86_64-linux-gnu/rubygems-integration/3.3.0/cache/ffi-1.17.0.gem
ls: cannot access
'/usr/lib/x86_64-linux-gnu/rubygems-integration/3.3.0/cache/ffi-1.17.0.gem':
No such file or directory
root@fum:/etc/schleuder# ls
/usr/lib/x86_64-linux-gnu/rubygems-integration/3.3.0/cache/f*
/usr/lib/x86_64-linux-gnu/rubygems-integration/3.3.0/cache/ffi-1.17.0-x86_64-linux-musl.gem
root@fum:/etc/schleuder#
Where did that `musl` come from?
