os.stat() throws an exception when applied to a dead
symlink (to a no longer existing file).
DESIRED: Catch exception (, report problem) and continue
ENCOUNTERED: On Cygwin platform.
Cygwin provides a directory /bin that is also mounted
as /usr/bin. Some package install relative symlinks
in /usr/bin. When processing the symlink in /bin, it does not
point to an existing file.