The latest version of media-libs/openexr in prefix-tree is media-libs/openexr-2.0.0, but there are ebuilds in gx86 that depend on >=media-libs/openexr-2.0.1, causing installation of those packages to break unless the offending package versions are manually masked.
Fixed in gx86. + 03 Aug 2014; Christoph Junghans <ottxor@gentoo.org> openexr-2.1.0.ebuild: + added prefix support (bug #515454) +