Update execute_in_sandbox to exit when sb command hits error
Update execute_in_sandbox to exit when sb command hits error

Change-Id: Ideb1cefc6f2f2134db11da36a00692ab198f59d5
RTC:69928
Reviewed-on: http://gfw160.austin.ibm.com:8080/gerrit/4131
Tested-by: Jenkins Server
Reviewed-by: Brian H. Horton <4d3586b959590a6e034649b5cc7435fb7d9ba30c@linux.ibm.com>
Reviewed-by: MIKE J. JONES <3bfb5759ff83ad3ac713f701b283073623a8cdd2@us.ibm.com>
Reviewed-by: A. Patrick Williams III <c87e37b1a4035affd737b461af89fb722d635f4d@us.ibm.com>

alvintpwang/hostboot,alvintpwang/hostboot,open-power/hostboot,csmart/hostboot,Over-enthusiastic/hostboot,Over-enthusiastic/hostboot,Over-enthusiastic/hostboot,open-power/hostboot,open-power/hostboot,csmart/hostboot,csmart/hostboot,alvintpwang/hostboot,open-power/hostboot,Over-enthusiastic/hostboot,alvintpwang/hostboot,csmart/hostboot,csmart/hostboot,Over-enthusiastic/hostboot,open-power/hostboot,alvintpwang/hostboot