The whole pattern already has `(...)*`, therefore there's no need to
make option_pattern optional.
Before this change, mount_condition_pattern could have matched
- on empty strings (it still can, thanks to the trailing `*` which can
also mean "zero matches") or
- whitespace-only strings (which is covered by the two regexes using
mount_condition_pattern - they both have `\s*` and/or `\s+` around it)
Known Bugs:
Will allow multiple letters in the () due to translation/unicode issues with regexing the key.
User input will probably bug out in a different locale.