[repo test] Avoid hangs in zmq repo unit test
- interaction through the zmq event loop from a different thread is only
allowed through add_callback
- notify the background thread when the client dies with an exception so it
doesn't spin forever
debian/tmp/usr/lib/PY_VERSION/site-packages/cubicweb/web usr/lib/PY_VERSION/site-packages/cubicweb
debian/tmp/usr/share/cubicweb/cubes/shared/data usr/share/cubicweb/cubes/shared
debian/tmp/usr/share/cubicweb/cubes/shared/wdoc usr/share/cubicweb/cubes/shared