[querier] test and fix potential bug in insertion query with multiple relations inside, caused by a name conflict. Also fix another bug non reproduced by using a set instead of a list (list may leads to compare entity instances which isn't allowed).
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