This is a duplicate of bug# 1731717.

I asked Donovan Baarda, who told me:

"""
Last time I looked this had been fixed, admittedly in a bit of an ugly
way, on the svn head. I offered to do a patch to make it a bit cleaner,
but as it isn't really broken anymore it was a bit of a low priority and
I haven't done it.

This bug seems to have a good repeatable test-case that we can probably
use in the unittests to show that it's now fixed...
"""