Drop initial query parameters on redirects

aiohttp/client.py

@@ -234,6 +234,7 @@ def _request(self, method, url, *,
                     r_url = urllib.parse.urljoin(url, r_url)
 
                 url = r_url
+                params = None
                 yield from resp.release()
                 continue
 

docs/client_reference.rst

@@ -133,7 +133,8 @@ The client session supports context manager protocol for self closing.
 
       :param params: Mapping, iterable of tuple of *key*/*value* pairs or
                      string to be sent as parameters in the query
-                     string of the new request (optional)
+                     string of the new request. Ignored for subsequent
+                     redirected requests (optional)
 
                      Allowed values are:
 

tests/test_client_functional.py

@@ -338,6 +338,28 @@ def handler(request):
         yield from resp.release()
 
 
+@pytest.mark.run_loop
+def test_drop_params_on_redirect(create_app_and_client):
+    @asyncio.coroutine
+    def handler_redirect(request):
+        return web.Response(status=301, headers={'Location': '/ok?a=redirect'})
+
+    @asyncio.coroutine
+    def handler_ok(request):
+        assert request.query_string == 'a=redirect'
+        return web.Response(status=200)
+
+    app, client = yield from create_app_and_client()
+    app.router.add_route('GET', '/ok', handler_ok)
+    app.router.add_route('GET', '/redirect', handler_redirect)
+
+    resp = yield from client.get('/redirect', params={'a': 'initial'})
+    try:
+        assert resp.status == 200
+    finally:
+        yield from resp.release()
+
+
 @pytest.mark.run_loop
 def test_history(create_app_and_client):
     @asyncio.coroutine