Description of problem:
repo delete fails if there is a repos in there are cloned repos but if the repos doesn't exist.

I had a repo (f15) I cloned, but I did a cancel clone which failed to cancel it completely. 
The cloned repo didn't get created but it still showed the following in the repo that was being cloned.

Clones             	[u'f15-clone', u'f15-clone1']

Related bug for this state is 

https://bugzilla.redhat.com/show_bug.cgi?id=760601

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


How reproducible:


Steps to Reproduce:
1. created f15 repo and synced
2. run repo clone
3.run cancel_clone at the end
4. repo list doesn't show the cloned repo but  the original repo shows the cloned repo
Clones             	[u'f15-clone', u'f15-clone1']

5. Try to delete the original repo (f15)
see the repo being deleted message

see the following in the pulp.log
and you can see that the repo does not get deleted

  
Actual results:
2012-01-11 10:12:00,956 10841:140055452575488: pulp.server.api.repo:INFO: repo:527 Delete API call invoked f15
2012-01-11 10:12:03,485 10841:140055452575488: pulp.server.tasking.task:ERROR: task:455 Task failed: Task 9a50fb66-3c66-11e1-92bb-002564a85a58: RepoApi.delete(, id=f15)
Traceback (most recent call last):
  File "/usr/lib/python2.7/site-packages/pulp/server/tasking/task.py", line 404, in run
    result = self.callable(*self.args, **self.kwargs)
  File "/usr/lib/python2.7/site-packages/pulp/server/api/repo.py", line 541, in delete
    cloned_repo = self._get_existing_repo(clone_id)
  File "/usr/lib/python2.7/site-packages/pulp/server/api/repo.py", line 116, in _get_existing_repo
    raise PulpException("No Repo with id: %s found" % id)
PulpException: No Repo with id: f15-clone found


Expected results:


Additional info: