Redirected URLs with multiple parameters not fashioned correctly

Problem/Motivation

We are using the module alongside Search API and Facets and as such we often have URLs with multiple parameters like this...

/challenges?f%5B0%5D=challenge_type_of_content%3Aexamination_question&f%5B1%5D=challenge_type_of_content%3Apick_n_mix&f%5B2%5D=challenge_type_of_content%3Astretch_activity

Note there the emboldened & elements.

After a r4032login redirection, the redirected URL is...
/challenges?f%5B0%5D=challenge_type_of_content%3Aexamination_question&amp%3Bf%5B1%5D=challenge_type_of_content%3Apick_n_mix&amp%3Bf%5B2%5D=challenge_type_of_content%3Astretch_activity&check_logged_in=1

(& replaced with &amp%)

The consequence of this is that when we finally it the Search API page, only the first facet filter gets used.