specifying php default argument results in bad argument sent when using ajax with tablesort

if you create a view using a php default argument, using a table style mode and ajax, when you sort on a column, the second argument of the path alias is send with the ajax query, rather than the result passed by php. oddly, the correct value is sent if exposing the filters and using that form. i haven't tested against pagination.

for example: create a view with a php default argument that grabs a taxonomy term from the given node page view, using pathauto, and the [title] part of content/[title] is sent as ?view_args=[title] rather than the correctly derived php defined argument.