Fixed tree name being passed in x_build_node_id call.

Fixed to pass in correct tree name to x_build_node_id method, it was blowing up when logged in user didnt have access to :sandt_tree.

https://bugzilla.redhat.com/show_bug.cgi?id=1115717
https://bugzilla.redhat.com/show_bug.cgi?id=1117993

@dclarizio please review/test.