Any known issues with https testing via proxy

Trying to get https testing working via proxy and works fine via curl but
xymon reports proxy 501 not implemented errors so I assume its showing up
malformed.  I see in sourceforce release notes a fix from 4.2 > 4.2.2 for
this related to Debian but I am running above this (4.3.17)


snip:

Changes from 4.2.0 -> 4.2.2 ===========================
 *) Patches from Debian and Mandriva source archives and
elsewhere have been merged, fixing: - The bb-hosts syntax for HTTP testing
via a proxy could not support https target-URL's (from Debian)

Thx in advance
Danny