When we use CPAchecker as verifier, CPAcheckers tool-info module
would see the output of the transformer and interpret it as an
"invalid-witness" status. This commit will remove the "Error:"
in front of that log message such that the tool-info module of
CPAchecker does not get fooled by it. This only affects 64bit
tasks in ReachSafety, currently that are only the AWS tasks.