Removing user from group or organization raises 404

[gt-novelt]

CKAN Version if known (or site URL)

This occurs on ckan 2.8.2 but might be older

Please describe the expected behaviour

You should be able to remove a user from a group or an organization.

Please describe the actual behaviour

I get a 404 and the user is not removed from group or organization.

What steps can be taken to reproduce the issue?

You need admin rights on a group or organization.
Get to the user list of the group or organization.
Click on the wrench of the user you want to remove.
You should be redirected to the "Edit Member" page.
Click on the delete button.
You get a 404.

Note that the delete button on the user list of the group or organization does work. Only the one in the edit member page does not.