Comment # 5 on bug 1123316 from Steffen Winterfeldt

I believe the intention of the code is to ensure only block devs or files are
used (versus pipes, char devs, dirs, etc). That it does not follow symlinks is
imho simply a bug.

Probably the fact that ruby's File.ftype does not follow links came as a
surprise
to the author (as possibly to nearly everybody).

File.blockdev? || File.file? would do the trick, I guess.