I've uploaded a quick workaround to check the above acl, it can be downloaded from here:
=> Test result: It works for me.
In the sense of the ITS title it's just a half-way workaround: It addresses only subtractive ACLs, additive ACLs are not addressed.
A clean solution, separating the bitmasks is of course preferable.
In my opinion ITS#6900 should be closed.