[ci] force downgrade of yarl for aiohttp tests (#402)

Author: Emanuele Palazzetti

.circleci/config.yml

@@ -146,7 +146,7 @@ jobs:
       - restore_cache:
           keys:
               - tox-cache-aiohttp-{{ checksum "tox.ini" }}
-      - run: tox -e '{py34,py35,py36}-aiohttp{12,13,20,21,22}-aiohttp_jinja{012,013}' --result-json /tmp/aiohttp.results
+      - run: tox -e '{py34,py35,py36}-aiohttp{12,13,20,21,22}-aiohttp_jinja{012,013}-yarl' --result-json /tmp/aiohttp.results
       - persist_to_workspace:
           root: /tmp
           paths:

tox.ini

@@ -27,7 +27,7 @@ envlist =
     {py27,py34,py35,py36}-ddtracerun
     {py34,py35,py36}-asyncio
     {py27}-pylons
-    {py34,py35,py36}-aiohttp{12,13,20,21,22}-aiohttp_jinja{012,013}
+    {py34,py35,py36}-aiohttp{12,13,20,21,22}-aiohttp_jinja{012,013}-yarl
     {py27}-tornado{40,41,42,43,44}
     {py27}-tornado{40,41,42,43,44}-futures
     {py34,py35,py36}-tornado{40,41,42,43,44}
@@ -77,6 +77,9 @@ deps =
 # test dependencies installed in all envs
     mock
     nose
+# force the downgrade as a workaround
+# https://github.com/aio-libs/aiohttp/issues/2662
+    yarl: yarl==0.18.0
 # integrations
     aiobotocore04: aiobotocore>=0.4,<0.5
     aiobotocore03: aiobotocore>=0.3,<0.4