Description:
Loading a celery application fails because python2-kombu imports anyjson without requiring it to be installed. anyjson *is* in the checkdepends, though.

Additional info:
* using python2-kombu 3.0.21-2
* kombu's anyjson requirement is satisfied with a normal pip install celery

Steps to reproduce:
* pacman -Sy python2-pip python2-kombu
* pip2 install --no-deps celery
* python2 -c "from celery import Celery"

Traceback (most recent call last):
File "<string>", line 1, in <module>
File "/usr/lib/python2.7/site-packages/celery/five.py", line 307, in __getattr__
module = __import__(self._object_origins[name], None, None, [name])
File "/usr/lib/python2.7/site-packages/celery/app/__init__.py", line 14, in <module>
from celery import _state
File "/usr/lib/python2.7/site-packages/celery/_state.py", line 20, in <module>
from celery.utils.threads import LocalStack
File "/usr/lib/python2.7/site-packages/celery/utils/__init__.py", line 25, in <module>
from kombu.entity import Exchange, Queue
File "/usr/lib/python2.7/site-packages/kombu/entity.py", line 12, in <module>
from .serialization import prepare_accept_content
File "/usr/lib/python2.7/site-packages/kombu/serialization.py", line 388, in <module>
register_json()
File "/usr/lib/python2.7/site-packages/kombu/serialization.py", line 310, in register_json
from anyjson import loads as json_loads, dumps as json_dumps
ImportError: No module named anyjson