base.py already looks for LD_SINGLEFILE_OPTIONS and defaults to "" when null; shlex.split("") returns [], so change should work when env variable unset
Tested with --user-agent <foo> and it worked on reddit (see linked issue)
Needs testing with multiple arguments, e.g. --user-agent <foo> --block-videos=true --block-audios=true
Closes #690
Needs some additional testing:
--user-agent <foo>
and it worked on reddit (see linked issue)--user-agent <foo> --block-videos=true --block-audios=true