Description of problem:
when importing storage domain fails under some conditions, for example when mount point is an empty directory, storage connection is still created,
so from the user perspective - when you are trying to create new storage domain on the same mount point because import failed, it fails with dialog window saying:
    Error while executing action: Cannot add Storage Connection. Storage connection already exists.


Version-Release number of selected component (if applicable):
3.3.0-0.24 (is17)

How reproducible:
always

Steps to Reproduce:
1. create empty nfs export
2. try to import this export as storage domain, this should fail, saying there is no storage domain
3. just click 'OK' button again, or hit 'Cancel' and try to create new storage domain on this export

Actual results:
you will get an error saying storage connection already exists, you have to delete this connection manually via api or in database

Expected results:
storage connection should not be created when import fails

Additional info:
this happens when import fails under some other contitions than those in steps to reproduce, too