I think the same problem exists for Europe/Belfast
A Link line for it is in file backwards, but this is not
compiled by default, so that no binary Europe/Belfast gets
created.
Adding a Link line in file europe would fix that.
Link Europe/London Europe/Belfast
I think file asia should have a line
Link Asia/Bangkok Asia/Hanoi
If this is absent, and file backzone is not compiled, no binary file for Hanoi gets created.
This breaks all references to it.For all other zones in backzone, a Link line exists so that a binary file is always created.