The quote characters are hard-coded into the operation of parse_line. There's no argument or switch that lets you tell it that you want double-quotes and back-slash escapes to recognized, but to treat single quotes as regular characters.

It looks like the only way to do what you want is to copy-and-paste the source code for sub parse_line into your script or module, and then go through and remove the ' characters from the key regexes -- for instance, changing "' to ".