upload_to_nexus to return a non-zero exit status

upload_to_nexus to return a non-zero exit status

As it turns out Nexus does not produce a http status code on upload
failure and returns back a blank message. This means if we do not
detect a successful status from Nexus we need to exit 1 explicity
to make sure we return to parallel a proper error status code.

JIRA: RELENG-765
Change-Id: Ic221c668bb6cd35befc614159ee8d7220d3f4cfe
Co-authored-by: Thanh Ha <thanh.ha@linuxfoundation.org>
Signed-off-by: Robert Varga <nite@hq.sk>
Signed-off-by: Thanh Ha <thanh.ha@linuxfoundation.org>