Fix flake8 errors

memcache.py

@@ -1442,7 +1442,8 @@ def readline(self, raise_exception=False):
         if self.socket:
             recv = self.socket.recv
         else:
-            recv = lambda bufsize: b''
+            def recv(bufsize):
+                return b''
 
         while True:
             index = buf.find(b'\r\n')

setup.py

@@ -15,7 +15,7 @@
     maintainer="Sean Reifschneider",
     maintainer_email="[email protected]",
     url="https://github.com/linsomniac/python-memcached",
-    download_url="https://github.com/linsomniac/python-memcached/releases/download/{0}/python-memcached-{0}.tar.gz".format(version),
+    download_url="https://github.com/linsomniac/python-memcached/releases/download/{0}/python-memcached-{0}.tar.gz".format(version),  # noqa
     py_modules=["memcache"],
     install_requires=open('requirements.txt').read().split(),
     classifiers=[