language switchers rendered incorrectly when arraving at WAYF via POST

[baszoetekouw]

Reproduce by:

• vists https://edu.nl/debug
• log in
• press retry
• view:

instead of

[thijskh]

Likely this is on purpose, as it's the only way to ensure the POST request remains a POST request while allowing to switch language?

[baszoetekouw]

Let's take this up in the general WAYF-makeover.