Comment 34 for bug 1476662

I think that the implementation of fusermount (file system in user space) had
similar problem, some code in this domain uses scheme, were process opens the
dir, chdirs in the other one and uses the /proc/self/fd elements in the mount

This is even resistent to moving/deleting and recreating the directory in
between, but I'm not sure, if it could be applied here also.