Maybe the sed script in file.sed is non-portable? It's certainly more
complex than the normal run-of-the-mill sed script. Or maybe it is that
the regex '.' has problems matching non-characters, and the definition
of the various locales determine whether 8-bit bytes are characters or
not. Is there any portable way to guarantee a single-byte locale where
'.' matches all possible 8-bit bytes?
More testing shows that 'LC_ALL=en_US.ISO8859-1 sed' on Darwin gives the
desired results, so the problem is definitely a matter of whether the C
locale treats all 256 byte values as potential matches to '.'.