Created attachment 369382 [details, diff] distcc-python.patch distcc-3.1-r9 uses the python-single-r1 eclass but it currently doesn't depend on Python at all. This was probably an oversight when switching from the older eclass. Python is needed in DEPEND and RDEPEND because pump uses it. See the attached patch. distcc-3.1-r7 also needs fixing in the same way.
3.2_rc1 seems to get it right...
3.2_rc1 still uses the old eclass.
Fixed in 3.2_rc1 a long time ago, closing this as OBSOLETE