Issue #975 with invalid materialization (#977)
Issue #975 with invalid materialization (#977)

merging test-only PRs

* Added test for issue #975.

* mark tests with ActiveIssue attribute

ronnyek/linq2db,MaceWindu/linq2db,linq2db/linq2db,LinqToDB4iSeries/linq2db,genusP/linq2db,genusP/linq2db,MaceWindu/linq2db,LinqToDB4iSeries/linq2db,linq2db/linq2db