mongodb/mongo-csharp-driver — pull request #172 by ddebilt (2014-02-15 21:35:25+00:00)
Title: CSHARP-900: Support downcasting object in LINQ queries

I ran into this issue and was able to get around it with the minor change in this pull request. Compilation requires the downcast, but it appears we just need to ignore the "convert" and create the appropriate Query regardless.