Make sure that blueprints with no slash is maintained when applied (#2085)

* Make sure that blueprints with no slash is maintained when applied

* Remove unneeded import

sanic/blueprints.py

@@ -85,7 +85,11 @@ class Blueprint(BaseSanic):
         self.routes: List[Route] = []
         self.statics: List[RouteHandler] = []
         self.strict_slashes = strict_slashes
-        self.url_prefix = url_prefix
+        self.url_prefix = (
+            url_prefix[:-1]
+            if url_prefix and url_prefix.endswith("/")
+            else url_prefix
+        )
         self.version = version
         self.websocket_routes: List[Route] = []
 

sanic/mixins/routes.py

@@ -71,7 +71,7 @@ class RouteMixin:
 
         # Fix case where the user did not prefix the URL with a /
         # and will probably get confused as to why it's not working
-        if not uri.startswith("/"):
+        if not uri.startswith("/") and (uri or hasattr(self, "router")):
             uri = "/" + uri
 
         if strict_slashes is None: