Add test cases for negative bitshift errors
Add test cases for negative bitshift errors

Same fix that was applied to v1.3 branch.

These tests confirm graceful handling of swivels with no buckets
enabled. If not handled properly, they would result in a negative
bitshift error.

Signed-off-by: Rene Fragoso <4f037aea503dc135aa921aed14c99ce156f74db7@gmail.com>

zumba/swivel,zumba/swivel