Summary says it all Reproducible: Always Steps to Reproduce:
python has now an xml flags 251298which make it depend on expat, so we just have to add dev-lang/python[xml] in deps (and switch to EAPI=2). See Bug #251298 for WIP ebuild with eapi=2
+ 21 Jul 2009; Samuli Suominen <ssuominen@gentoo.org> gajim-0.12.1.ebuild: + dev-lang/python needs to be built with USE xml wrt #254870.