Synonyms are scored more harshly when there are > 2

[nolanlawson]

Consider the synonyms:

dog,hound,pooch

And a document containing:

dog

We would expect a query for dog, pooch, and hound to arrive at the same score, assuming synonyms.originalBoost and synonyms.synonymBoost are both set to 1.0.

However, hound and pooch are scored less than dog. Apparently this has to do with the DisjunctionMaxQuery math and the fact that there are more than two synonyms. E.g. when the synonyms are just:

dog,hound

the scores are equal.