We default to the jmp-hash method which we had previously, and allow a
user to set the "modulus" option which uses a simple mod operation to
ensure an even spread of partitions across nodes.
I think that ideally we would have new indexes uses modulus and
existing indexes use jmp-hash which implies supporting this
configuration on a per-index basis.
If we don't do per index, we should probably run the whole test suite
both ways.
we change this to use a simple modulus to ensure maximally even
assignment of partitions to nodes rather than the hash thing we were
doing previously which may have helped minimize data movement when
adding nodes, though I'm not even sure of that.
The logic was duplicated in a few places, so we've also condensed
that. For now, we're skipping tests which have baked in assumptions
about which node a partition will end up on as we expect them to fail
until they are updated.
i used this script, a little clunky but it got the job done
```bash
for file in `find . -type f -print | grep '\.go'`; do
sed '1,/^\/\/ limitations under the License.$/d' $file > $file.tmp;
result=`cat $file.tmp`
if [[ result != "" ]]; then
gofmt $file.tmp &> /dev/null;
if [[ $? == 0 ]]; then
mv $file.tmp $file && gofmt -w $file;
else
rm $file.tmp;
fi
else
rm $file.tmp;
fi
done
```
Turns out we sometimes modify returned nodes. Handle this better, but
also fix up some cases where we were generating node lists we didn't really
need to answer simple questions.
