Finally, just avoid --upgrade overall

gitlab/before_test.sh

@@ -16,13 +16,13 @@ else
   log_info "Using pip: ${use_pip}"
 fi
 
+# zc.recipe.egg needs some special installation instructions
 if [ "${CI_PROJECT_NAME}" == "bob.buildout" ]; then
-  # zc.buildout requires special handling
-  run_cmd ${use_pip} install --pre dist/*.whl
-else
-  run_cmd ${use_pip} install --upgrade --use-wheel --no-index --pre dist/*.whl
+  run_cmd ${use_pip} install --no-binary ":all:" zc.recipe.egg
 fi
 
+run_cmd ${use_pip} install --use-wheel --no-index --pre dist/*.whl
+
 # Downloads databases that may be missing (not shipped with python pkg)
 if [ -x ${PREFIX}/bin/bob_dbmanage.py ]; then
   run_cmd ${PREFIX}/bin/bob_dbmanage.py all download --missing;