This is similar to the combination of PORTAGE_RO_DISTDIRS and DISTDIR. For example, a closed environment (chroot, lxc, etc) for building packages where an existing PKGDIR is mounted RO but new packages built should be placed in a writable path. Reproducible: Always
Since PORTAGE_BINHOST already allows an arbitrary number of binhosts, this could be implemented as file:// URI support in PORTAGE_BINHOST.
(In reply to Zac Medico from comment #1) > Since PORTAGE_BINHOST already allows an arbitrary number of binhosts, this > could be implemented as file:// URI support in PORTAGE_BINHOST. This was done with bug 920537 \o/