PROJ1664: Change error messages to be more informative
PROJ1664: Change error messages to be more informative

This patch changes the exception messages returned to the user so they
now use invokebuild instead of cmd or invokeself.

Reviewed-by: Scott Parlane <85029adc3fa41ef14594a57826619713bfe95f25@alliedtelesis.co.nz>

alliedtelesis/buildsyspp,ATL-NZ/buildsyspp