Don't allow jobs without Redis connection.

And other connection-related fixes.

rq/job.py

@@ -4,7 +4,8 @@ import times
 from collections import namedtuple
 from uuid import uuid4
 from cPickle import loads, dumps, UnpicklingError
-from .connections import get_current_connection
+from .local import LocalStack
+from .connections import resolve_connection
 from .exceptions import UnpickleError, NoSuchJobError
 
 
@@ -135,9 +136,9 @@ class Job(object):
         return self._kwargs
 
     @classmethod
-    def exists(cls, job_id):
+    def exists(cls, job_id, connection=None):
         """Returns whether a job hash exists for the given job ID."""
-        conn = get_current_connection()
+        conn = resolve_connection(connection)
         return conn.exists(cls.key_for(job_id))
 
     @classmethod
@@ -150,9 +151,7 @@ class Job(object):
         return job
 
     def __init__(self, id=None, connection=None):
-        if connection is None:
-            connection = get_current_connection()
-        self.connection = connection
+        self.connection = resolve_connection(connection)
         self._id = id
         self.created_at = times.now()
         self._func_name = None

rq/queue.py

@@ -98,7 +98,7 @@ class Queue(object):
             job_id = self.connection.lpop(COMPACT_QUEUE)
             if job_id is None:
                 break
-            if Job.exists(job_id):
+            if Job.exists(job_id, self.connection):
                 self.connection.rpush(self.key, job_id)