If /tmp and /nix are in different filesystems, this causes the `find`s
in the fixup phase to fail because of a stale file handle:
find: cannot get current directory: No such file or directory
There are many more packages to fix, this is just a start.
Rules:
* Don't repeat the package name (not always that easy...)
* Start with capital letter
* Don't end with full stop
* Don't start with "The ..." or "A ..."
I've also added descriptions to some packages and rewritten others.
