[request] Ensure base_url() always has a trailing '/' (closes #3955093)
Just as an example, cubicweb.ajax.js is clearly written under the
assumption that BASE_URL/baseuri() - which simply contains req.base_url() - has a
trailing /.
/* * cubicweb js mock for unit tests * This module defines variables and functions used in quite a few places * in cw js framework that can't be used or guessed without a real CW server */varpageid='my-page-id';function_(message){returnmessage;}