Lately (it is at least in the current CVS, not sure if it's already in some
release), ftw() and relatives were converted to use fxstatat(). The trouble is,
this will not work right with kernels not supporting the appropriate syscall:
then it is emulated by looking into /proc/self/fd/, but in case the executable
was setuid root and then the process setuid()s to a non-root user, /proc/self/fd
becomes inaccessible to it. And unfortunately, the LSB testsuite uses exactly
this setup when testing nftw().

The simple fix would be to make ftw() double-check with lstat() if fxstatat() 
returns error or not use fxstatat() altogether; I'm not sure if this could be
fixed properly in fxstatat() itself.