Fix the conditional here.

Fix the conditional here.

We do always need a trailing slash if we have a server path and either
just a /, or no uri at all (e.g. http://localhost). This matters when
we're mounted at a non-root path, as cataltst needs to see
http://localhost/non_root_path/, rather than http://localhost/non_root_path,
otherwise we'll try to resolve /non_root path as an action.