bcd8ec89c6105 replaced Family.nicepath with APISite.article_path , and implemented Page.full_url using APISite.article_path
APISite.article_path currently requires that siteinfo attribute articlepath ends with $1, and uses an assert to confirm this.
There is at least one site on the IWM where the articlepath which does not end with $1
In that case, the trailing / is not necessary when accessing the site; URLs without the trailing / work correctly.
So, it would be possible to ignore the trailing /.
However, a bigger problem exists if there are sites which require something after the $1.