[rb-general] lzip/plzip alternatives

[Sylvain]

Hi,

I played with reproducible tarballs and noticed that the Debian
packages for lzip and plzip (parallel lzip) manage /usr/bin/lzip
through an alternatives (symlinks) system.
Installing plzip makes /usr/bin/lzip point to that variant.

AFAICT compressors and their parallel variants produce different
output, and this is the case here.

This means that if I produce my tarball using 'tar -c --lzip' or
'tar -c | lzip', depending on whether plzip is installed or not, I
will silently get a different output.

Should I file a bug report against the plzip package?
What severity would you recommend?

(Bonus question: is it theoretically possible to have such tools pairs
 (gz/pigz, xz/pgz, lzip/plzip) produce the same output? :))

Cheers!
Sylvain