[test] return the failed command output only in Verbose mode
[test] return the failed command output only in Verbose mode

Change-Id: I6c4433c22f5a52f947329155d0cfd475a99b86e0

lebauce/skydive,safchain/skydive,lebauce/skydive,lebauce/skydive,lebauce/skydive,skydive-project/skydive,redhat-cip/skydive,safchain/skydive,lebauce/skydive,skydive-project/skydive,safchain/skydive,skydive-project/skydive,lebauce/skydive,skydive-project/skydive,lebauce/skydive,skydive-project/skydive,safchain/skydive,skydive-project/skydive,redhat-cip/skydive,redhat-cip/skydive,safchain/skydive,safchain/skydive,lebauce/skydive,safchain/skydive,skydive-project/skydive,safchain/skydive