fabric/fabric — pull request #1213 by ipanousis (2014-10-22 11:15:13+00:00)
Title: Include error message in task abort exception

According to https://docs.python.org/2/library/sys.html the sys.exit([arg]) call will still result in error code of 1 for any non-zero object given. But at least by providing the error message it can be caught and inspected by the running program first.