Some OpenSolaris/illumos-based distribution used various Linux package
managers such as dpkg, rpm, and portage (see more at
http://wiki.illumos.org/display/illumos/Distributions). It would make
sense for Solaris' case to be unified with Linux.

However, Linux's `pkg` detection (I don't know which distro is that) are
vastly different from Oracle Solaris/OpenIndiana's `pkg`, so a
workaround is used.