Prior to the introduction of HTSlib, SAMtools and BCFtools were distributed
in a single samtools-0.1.x package.
This old version remains available from SBo as samtools-legacy

HTSlib has been distributed as a separate package to facilitate the writing
of programs against the HTSlib API. HTSlib also provides the bgzip, htsfile,
and tabix utilities, so the installation of HTSlib provides these utilities as well.