jnunemaker/plucky — pull request #29 by paulwalker (2012-12-31 02:35:30+00:00)
Title: do not normalize to $in operator with an empty array

illustration of issue

> db.foo.insert({ bar: [] })
> db.foo.find({ bar: { $in: [] } }).count()
0
> db.foo.find({ bar: [] }).count()
1