I was investigating what needs to be done to drop guile-1.8 from the tree (bug 590558, 587252). sci-chemistry/coot is one of the blocking packages (bug 591410). It has a version bump request open for 18 months (bug 639760) and hasn't been maintained in as long. The new version doesn't appear to work with guile-2.0 either, though it seems that it may be possible to build without guile? Something for a maintainer...
If we just drop it, we can remove the following dependencies as well: sci-chemistry/coot (no rev deps) sci-libs/coot-data (rev deps: sci-chemistry/coot) sci-libs/ssm (rev deps: sci-chemistry/coot) sci-libs/gpp4 (no rev deps) sci-libs/cctbx (no rev deps) sci-libs/clipper (rev deps: sci-chemistry/coot, sci-libs/cctbx) sci-libs/libccp4 (rev deps: sci-chemistry/coot, sci-libs/{clipper,ssm} sci-libs/monomer-db (rev deps: sci-chemistry/coot) sci-libs/mmdb (rev deps: sci-chemistry/coot, sci-libs/{clipper,gpp4,libcpp4,ssm} sci-chemistry/reduce (rev deps: sci-chemistry/coot) dev-scheme/guile-gui (rev deps: sci-chemistry/coot; dead home page) dev-scheme/guile-www (rev deps: sci-chemistry/coot) dev-scheme/net-http (rev deps: sci-chemistry/coot; dead home page) x11-libs/guile-gtk (rev deps: dev-scheme/guile-gui, dev-scheme/guile-gui) Thoughts?