CORE-13974
This should fix situations where (for example):
command_1 | command_2 && echo Succeeded
should *NOT* run "echo Succeeded" if any of the command_1 or command_2 has
failed.
This also makes the ExecutePipeline() function on par with the other
"ExecuteXXX()" helpers.
Problem diagnosed by Doug Lyons; patch inspired by contributor 'cagey45'.