scp aborts with:
xfree: NULL pointer given as argument
when a LocalForward config exists.
http://bugzilla.mindrot.org/show_bug.cgi?id=996 has a patch. It also says that
it will be included in the next release of openssh. So I don't know if it is
necessary to fix this now or just wait for the next release. I would prefer if
it is fixed now but I also know how to circumvent this bug.