$ find /usr/lib64/python2.7/site-packages/grc_gnuradio/ /usr/lib64/python2.7/site-packages/grc_gnuradio/ /usr/lib64/python2.7/site-packages/grc_gnuradio/__init__.py /usr/lib64/python2.7/site-packages/grc_gnuradio/wxgui /usr/lib64/python2.7/site-packages/grc_gnuradio/wxgui/panel.py /usr/lib64/python2.7/site-packages/grc_gnuradio/wxgui/__init__.py /usr/lib64/python2.7/site-packages/grc_gnuradio/wxgui/top_block_gui.py /usr/lib64/python2.7/site-packages/grc_gnuradio/blks2 /usr/lib64/python2.7/site-packages/grc_gnuradio/blks2/packet.py /usr/lib64/python2.7/site-packages/grc_gnuradio/blks2/error_rate.py /usr/lib64/python2.7/site-packages/grc_gnuradio/blks2/selector.py /usr/lib64/python2.7/site-packages/grc_gnuradio/blks2/tcp.py /usr/lib64/python2.7/site-packages/grc_gnuradio/blks2/__init__.py Fixed for me by adding python_mod_optimize grc_gnuradio and python_mod_cleanup grc_gnuradio to pkg_postinst and pkg_postrm. Should presumeably be within the if use grc's.
Looks like there is also /usr/lib64/python2.7/site-packages/gruel/. But there is a SWIG generated file in there.
not sure exactly when this was fixed, never noticed the bug. but the latest ebuilds are fine.