Pathauto strips special characters from inside tokens

Using a token such as [term:parents:join:?] allows you to split an array of variables by a string.

[term:parents:join:string] performs as expected and produces the url "termstringtermstringterm"

[term:parents:join:/] does not perform as expected: "termtermterm"

Using hex codes as an attempt at a workaround I discovered the problem:
[term:parents:join:%2f] results in "term2fterm2fterm" - Pathauto is stripping the special characters from this token as it would from the term title.

This is a tricky one as the term names should be parsed but the splitter string shouldn't be.