This seems to be a consequence of nsGNOMERegistry::HandlerExists checking that a handler exists using the old gconf values (which it shouldn't be doing now), before doing the actual launch in nsGNOMERegistry::LoadURL using gio (which works correctly if it ever gets to that stage).
This seems to be a consequence of nsGNOMERegistry ::HandlerExists checking that a handler exists using the old gconf values (which it shouldn't be doing now), before doing the actual launch in nsGNOMERegistry ::LoadURL using gio (which works correctly if it ever gets to that stage).
Should be a fairly trivial fix