Not exactly. His problem arised at new(), and my problem arised at filename(). My call to new() went without a problem, as my Email::MIME already contained his patch.
However, following his example, I patched the filename() method, and my problem vanished. I changed
my $dis = $self->header("Content-Disposition") || '';
to:
my $dis = $self->header_raw("Content-Disposition") || '';