Disable strict_slashes for Flask so that S3 works in server mode.

moto/s3/urls.py

@@ -21,9 +21,7 @@ url_paths = {
     '{0}/$': S3ResponseInstance.bucket_response,
 
     # subdomain key of path-based bucket
-    '{0}/(?P<key_or_bucket_name>[^/]+)$': ambiguous_response1,
-    # subdomain key of path-based bucket
-    '{0}/(?P<key_or_bucket_name>[^/]+)/$': ambiguous_response2,
+    '{0}/(?P<key_or_bucket_name>[^/]+)/?$': S3ResponseInstance.ambiguous_response,
     # path-based bucket + key
     '{0}/(?P<bucket_name_path>[^/]+)/(?P<key_name>.+)': S3ResponseInstance.key_response,
 }

moto/server.py

@@ -113,6 +113,7 @@ def create_backend_app(service):
             endpoint=endpoint,
             methods=HTTP_METHODS,
             view_func=convert_flask_to_httpretty_response(handler),
+            strict_slashes=False,
         )
 
     backend_app.test_client_class = AWSTestHelper