Description of problem:
there is a discrepancy in _href attribute of a task object when fetched /pulp/api/v2/tasks/ and /pulp/api/v2/task_groups/


Version-Release number of selected component (if applicable):
Pulp 2.2

How reproducible:
Always

Steps to Reproduce:
1. GET /pulp/api/v2/tasks/<task_id>/
2. _href points to /pulp/api/v2/tasks/<task.task_id>/
3. GET /pulp/api/v2/task_groups/<task.task_group_id>/
4. a list of objects is returned such that each object _href attribute points to /pulp/api/v2/task_groups/<task.task_group_id>/

Actual results:
there is a discrepancy in _href attribute of a task object when fetched /pulp/api/v2/tasks/ and /pulp/api/v2/task_groups/

Expected results:
the _href attribute of a task object always points to the object location in /tasks/<task.task_id>/

Additional info:
# Screen log
>preprequest:
>m GET
>p https://ec2-54-217-149-4.eu-west-1.compute.amazonaws.com/pulp/api/v2/task_groups/11293f3d-7436-4952-9a7d-2ddd91afde1d/
>b {}
>h CaseInsensitiveDict({'Content-Length': u'2', 'Content-Type': 'application/json', 'Authorization': u'Basic YWRtaW46YWRtaW4='})

>response:
>c 200
>u https://ec2-54-217-149-4.eu-west-1.compute.amazonaws.com/pulp/api/v2/task_groups/11293f3d-7436-4952-9a7d-2ddd91afde1d/
>t [{"task_group_id": "11293f3d-7436-4952-9a7d-2ddd91afde1d", "exception": null, "traceback": null, "_href": "/pulp/api/v2/task_groups/11293f3d-7436-4952-9a7d-2ddd91afde1d/", "task_id": "a0f20d73-e5df-47f9-8b8b-19405afe4c29", "call_request_tags": ["pulp:repository:SimpleRepoTest_repo", "pulp:action:sync"], "reasons": [], "start_time": "2013-10-11T10:07:31Z", "tags": ["pulp:repository:SimpleRepoTest_repo", "pulp:action:sync"], "state": "running", "finish_time": null, "dependency_failures": {}, "schedule_id": null, "progress": {"yum_importer": {"content": {"size_total": 0, "items_left": 0, "items_total": 0, "state": "NOT_STARTED", "size_left": 0, "details": {"rpm_total": 0, "rpm_done": 0, "drpm_total": 0, "drpm_done": 0}, "error_details": []}, "comps": {"state": "NOT_STARTED"}, "distribution": {"items_total": 0, "state": "NOT_STARTED", "error_details": [], "items_left": 0}, "errata": {"state": "NOT_STARTED"}, "metadata": {"state": "IN_PROGRESS"}}}, "call_request_group_id": "11293f3d-7436-4952-9a7d-2ddd91afde1d", "call_request_id": "a0f20d73-e5df-47f9-8b8b-19405afe4c29", "principal_login": "admin", "response": "accepted", "result": null}]

>preprequest:
>m GET
>p https://ec2-54-217-149-4.eu-west-1.compute.amazonaws.com/pulp/api/v2/tasks/a0f20d73-e5df-47f9-8b8b-19405afe4c29/
>b {}
>h CaseInsensitiveDict({'Content-Length': u'2', 'Content-Type': 'application/json', 'Authorization': u'Basic YWRtaW46YWRtaW4='})

>response:
>c 200
>u https://ec2-54-217-149-4.eu-west-1.compute.amazonaws.com/pulp/api/v2/tasks/a0f20d73-e5df-47f9-8b8b-19405afe4c29/
>t {"task_group_id": "11293f3d-7436-4952-9a7d-2ddd91afde1d", "exception": null, "traceback": null, "_href": "/pulp/api/v2/tasks/a0f20d73-e5df-47f9-8b8b-19405afe4c29/", "task_id": "a0f20d73-e5df-47f9-8b8b-19405afe4c29", "call_request_tags": ["pulp:repository:SimpleRepoTest_repo", "pulp:action:sync"], "reasons": [], "start_time": "2013-10-11T10:07:31Z", "tags": ["pulp:repository:SimpleRepoTest_repo", "pulp:action:sync"], "state": "running", "finish_time": null, "dependency_failures": {}, "schedule_id": null, "progress": {"yum_importer": {"content": {"size_total": 78564, "items_left": 32, "items_total": 32, "state": "IN_PROGRESS", "size_left": 78564, "details": {"rpm_total": 32, "rpm_done": 0, "drpm_total": 0, "drpm_done": 0}, "error_details": []}, "comps": {"state": "NOT_STARTED"}, "distribution": {"items_total": 0, "state": "NOT_STARTED", "error_details": [], "items_left": 0}, "errata": {"state": "NOT_STARTED"}, "metadata": {"state": "FINISHED"}}}, "call_request_group_id": "11293f3d-7436-4952-9a7d-2ddd91afde1d", "call_request_id": "a0f20d73-e5df-47f9-8b8b-19405afe4c29", "principal_login": "admin", "response": "accepted", "result": null}