foursquare/fongo — pull request #9 by tobyclemson (2012-12-16 20:04:48+00:00)
Title: Allow update object to contain an _id field even if query object is not just an _id as long as the _ids are equal.

When performing an update, the only limitation imposed is that the _id field cannot be changed. It is perfectly acceptable for an update that has a query object that is not just an _id query, i.e., it has more key-values specified to also have the _id present in the object used for the update.

This change updates existing tests and adds another to capture this case. It also makes the required changes to the implementation of ```FongoDBCollection```