[autotest] Replace NotImplemented with NotImplementedError.

Python already has an exception that represents a chunk of code not
being implemented.

TEST=pylint
BUG=None

Change-Id: I21259163d49a36fa47fae7f86d0585295237fa35
Reviewed-on: https://gerrit.chromium.org/gerrit/36570
Tested-by: Alex Miller <milleral@chromium.org>
Reviewed-by: Wade Guthrie <wdg@google.com>
Reviewed-by: Christopher Wiley <wiley@chromium.org>
Commit-Ready: Alex Miller <milleral@chromium.org>
1 file changed