Fix #444 - Search was not scoped to repo. r=karlcow

This happened because params is a MultiDict, so update doesn't
do what I thought it would do. MultiDict is allowed to have multiple
keys that are the same.

Author: Mike Taylor

webcompat/api/endpoints.py

@@ -163,7 +163,7 @@ def get_search_results(query_string=None):
         query_string = params.get('q')
         # restrict results to our repo.
     query_string += " repo:{0}".format(REPO_PATH)
-    params.update({'q': query_string})
+    params['q'] = query_string
 
     if g.user:
         request_headers = get_request_headers(g.request_headers)