derive more of https from http method

derive more of https from http method

Bug #778375 uncovered that https wasn't properly integrated in the class
family tree of http as it was supposed to be leading to a NULL pointer
dereference. Fixing this 'properly' was deemed to much diff for
practically no gain that late in the release, so commit
0c2dc43d4fe1d026650b5e2920a021557f9534a6 just fixed the synptom, while
this commit here is fixing the cause plus adding a test.