[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 /.
[MESSAGES CONTROL]
disable-msg = C0301
[VARIABLES]
# Enable / disable this checker
enable-variables = yes
additional-builtins = _, display_name
[BASIC]
required-attributes=
attr-rgx = (w|[a-z_][a-z0-9_]{2,30})
variable-rgx = (w|[a-z_][a-z0-9_]{2,30})$
argument-rgx = (w|[a-z_][a-z0-9_]{2,30})$
[TYPECHECK]
generated-members=debug,info,notice,warning,error,critical,exception