The upstream used naming for python-config is 'pythonX.Y-config'. Please fix your package to use that rather than relying on Gentoo-specific 'python-config-X.Y'. This can be often fixed by removing some patch, sed or configure override.
It was done on purpose at: [[ ${EPYTHON} == python2* ]] && G2CONF+=" --enable-python2 --disable-python3 PYTHON2_CONFIG=/usr/bin/python-config-${EPYTHON#python}" [[ ${EPYTHON} == python3* ]] && G2CONF+=" --enable-python3 --disable-python2 PYTHON3_CONFIG=/usr/bin/python-config-${EPYTHON#python}" Otherwise it wasn't working... feel free to update it when needed :)
A modern note: if you're using python-r1, python-single-r1 or python-any-r1, it's not necessary to use 'python-config-X.Y' or 'pythonX.Y-config' anymore. The eclass puts a local symlink to proper 'python-config' variant in $PATH, so the build system can just take 'python-config' and it will get the version desired. If the build system in question respects PYTHON and looks for appropriate pythonX.Y-config itself, great! If it doesn't, there's no need to hack it in. Just let it use python-config and the eclass will do the rest.
+*libpeas-1.10.1 (04 Sep 2014) + + 04 Sep 2014; Pacho Ramos <pacho@gentoo.org> +libpeas-1.10.1.ebuild, + -libpeas-1.9.0.ebuild, metadata.xml: + Version bump, use new python-config (#488392 by mgorny), drop old. +