Comment 9 for bug 1226227

Looks like unity-mir would really need to re-implement mir::options::ProgramOption and pass our own version back in an overridden version of the_options().

ProgramOption actually makes the call to parse_command_line() internally, its variable_maps instance that holds all the parsed options is private, and it doesn't expose any other way to set the options. So that's where the action is.

Unfortunately, we'd have to just copy the chunks of code for parse_environment() and parse_file().