Enrich test-suite with a test for #2734

git-svn-id: svn+ssh://scm.gforge.inria.fr/svn/coq/branches/v8.4@16366 85f007b7-540e-0410-9357-904b9bb8a0f7
Enrich test-suite with a test for #2928

git-svn-id: svn+ssh://scm.gforge.inria.fr/svn/coq/branches/v8.4@16368 85f007b7-540e-0410-9357-904b9bb8a0f7