Fix non existence test

software/erp5/software.cfg

@@ -9,7 +9,6 @@ versions = versions
 develop =
   ${:parts-directory}/slapos.cookbook-repository
   ${:parts-directory}/cloudooo-repository
-  # ${:parts-directory}/vifib
 
 parts +=
 # Local development
@@ -41,7 +40,7 @@ update-command = cd "${:location}" && "${git:location}/bin/git" fetch --quiet &&
 recipe = plone.recipe.command
 stop-on-error = true
 update-command = ${:command}
-command = grep -v parts ${buildout:develop-eggs-directory}/slapos.core.egg-link
+command = test ! -e ${buildout:develop-eggs-directory}/slapos.core.egg-link
 
 [check-recipe]
 recipe = plone.recipe.command