The current code in 2.0/2.2/trunk does not set the SERVER_PORT_SECURE correctly. When HTTPS is set to "on" then the mod_isapi code is supposed to set SERVER_PORT_SECURE to 1. However, the code does not compare the string correctly.
Created attachment 18896 [details] Patch against 2.0.59 Trivial fix
I concur... http://svn.apache.org/viewvc?view=rev&revision=492341 Thanks for the submission!