Revert "bug #9601 [Routing] Remove usage of deprecated _scheme requirement (Danez)"

This reverts commit 0af3d19c3855b18a8742b82b1d1ea7fe8535c412, reversing
changes made to d56cc4b2cb3236a4c1dda4bfc8f09fdf13248536.
Merge branch '2.3' into 2.4

* 2.3:
  Revert "bug #9601 [Routing] Remove usage of deprecated _scheme requirement (Danez)"