When given a unexisted taskID, the koji cli will report some errors like follows
TypeError: 'NoneType' object has no attribute '__getitem__'
This patch will will give a message like follows
GenericError: No such task: 20024588
+1
-1 GenericError is undefined. Needs to be koji.GenericError
rebased
@mikem fixed. Pls review.
Commit 1158070b fixes this pull-request
Pull-Request has been merged by mikem@redhat.com