This option provides a more convenient way to overlay dummy packages.
It also adds a function `config.lib.test.mkStubPackage` that can,
e.g., be used for `package` options.
The option to remove the default keybindings by setting the
`programs.qutebrowser.enableDefaultKeybindings` variable to `false`
had a list wrapped around the `config.py` line. This would cause a
type coercion error.
PR #1410
