Fixed double-quoted URL bug in MapAdapter.get_default_redirect

default redirecting generates double-quoted URLs

What we expect is:
http://localhost:4000/ham%20egg/page/1
↓(redirection)
http://localhost:4000/ham%20egg

But werkzeug does:
http://localhost:4000/ham%20egg/page/1
↓(redirection)
http://localhost:4000/ham%2520egg