require irb/completion
ZypperError with proper message if call returns bad exit status and error message is empty
fix typo
Merge pull request #114 from SUSE/review_140617_should_raise_zyppererror_with_proper_message_if_call_returns_bad_exit_status_and_error_message_is_emptyzyppererror_with_proper_message_if_call_returns_bad_exit_status_and_error_message_is_empty

[Review] Request from 'vlewin' @ 'SUSE/connect/review_140617_should_raise_zyppererror_with_proper_message_if_call_returns_bad_exit_status_and_error_message_is_empty