Some characters are url-encoded, making url parameters fail

I'm trying to make views_megarow work with a url parameter, but I cannot get it to work because the ? and = characters are url-encoded, and apparently Drupal does not accept these.

I add a megarow like Create item|node/add/article?field_myfield=[field_myfield]. This outputs a link like display_megarow/3/node/add/article%3Ffield_myfield%3D9, which is displayed as the Megarow content "You have not created any content types yet. Go to the content type creation page to add a new content type".

This must be because node/add/article%3Ffield_myfield%3D9 is not found and goes to the node/add overview, while node/add/article?field_myfield=9 does work, and correctly prepopulates the field using entityreference_prepopulate.

I wonder why the slashes in node/add/article are not replaced with their hexadecimal variant %2F, but ? and = become %3F and %3D.

Can views_megarow support non-url-encoded characters in order to make url parameters work?