thanks for the followup post. We continued the discussion with Paolo Bonzini in private, and in the end, I released a new version (0.23) of lbzip2.

Before this release, lbzip2 ignored SIGPIPE, no matter what action it inherited, and an EPIPE write() condition was honored as any other fatal error, ie. with exit status 1. I still consider this way of handling EPIPE completely OK, but since I could implement process termination with SIGPIPE fairly cleanly for this case, I thought I’d follow the default behavior of traditional UNIX(R) utilities more closely, and also improve lbzip2′s compatibility with GNU tar.

Any user who wants the previous behavior can bequeath a SIG_IGN action to lbzip2 for SIGPIPE, as in

$ (trap '' SIGPIPE && lbzip2 ...)