Stupid zsh is messing with our beloved ksh heritage :chicken:

Closes #2038

docs/includes/installation.txt

@@ -28,9 +28,9 @@ commas.
 
 .. code-block:: bash
 
-    $ pip install celery[librabbitmq]
+    $ pip install "celery[librabbitmq]"
 
-    $ pip install celery[librabbitmq,redis,auth,msgpack]
+    $ pip install "celery[librabbitmq,redis,auth,msgpack]"
 
 The following bundles are available: