efcore: EF Core 1.1.1 has introduced a new ArgumentException for complex queries with with subqueries, if the same subquery is present multiple times in the query model

I saw today that EF Core 1.1 has been released. I made a new branch and upgraded from 1.0. Now several of our integration tests are failing with the below error. I’m not going to attempt to give you the full code base that raises this error; our codebase is massive. Rather I will just paste the line of code that throws the error along with the stack trace and hope this will be helpful to you. In the meantime I’m abandoning my attempt to upgrade until I hear back that this bug has been repaired.

The line of code that raises the exception:

                            var result = pagedResult
                                .Select(bt => new LibraryManagerSubShelf
                                {
                                    TitleStartingLetter = bt.titleStartingLetter.ToUpper()
                                })
                                .ToList();

where pagedResult is an IQueryable<> that has had a .Skip().Take() applied to it. I verified that if the skip+take is removed, the exception is not thrown.

Stack trace:

System.ArgumentException: An item with the same key has already been added.
   at System.ThrowHelper.ThrowArgumentException(ExceptionResource resource)
   at System.Collections.Generic.Dictionary`2.Insert(TKey key, TValue value, Boolean add)
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryModelExtensions.QueryModelMappingPopulatingVisitor.VisitSubQuery(SubQueryExpression expression)
   at Microsoft.EntityFrameworkCore.Query.ExpressionVisitors.ExpressionVisitorBase.Visit(Expression node)
   at System.Linq.Expressions.ExpressionVisitor.VisitAndConvert[T](ReadOnlyCollection`1 nodes, String callerName)
   at Remotion.Linq.Parsing.RelinqExpressionVisitor.VisitNew(NewExpression expression)
   at Microsoft.EntityFrameworkCore.Query.ExpressionVisitors.ExpressionVisitorBase.Visit(Expression node)
   at Remotion.Linq.Clauses.SelectClause.TransformExpressions(Func`2 transformation)
   at Remotion.Linq.QueryModel.TransformExpressions(Func`2 transformation)
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryModelExtensions.QueryModelMappingPopulatingVisitor.VisitSubQuery(SubQueryExpression expression)
   at Microsoft.EntityFrameworkCore.Query.ExpressionVisitors.ExpressionVisitorBase.Visit(Expression node)
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryModelExtensions.PopulateQueryModelMapping(QueryModel queryModel, Dictionary`2 mapping)
   at Microsoft.EntityFrameworkCore.Query.RelationalQueryModelVisitor.LiftSubQuery(IQuerySource querySource, Expression itemsExpression, Expression expression)
   at Microsoft.EntityFrameworkCore.Query.EntityQueryModelVisitor.VisitMainFromClause(MainFromClause fromClause, QueryModel queryModel)
   at Remotion.Linq.QueryModelVisitorBase.VisitQueryModel(QueryModel queryModel)
   at Microsoft.EntityFrameworkCore.Query.EntityQueryModelVisitor.VisitQueryModel(QueryModel queryModel)
   at Microsoft.EntityFrameworkCore.Query.RelationalQueryModelVisitor.VisitQueryModel(QueryModel queryModel)
   at Microsoft.EntityFrameworkCore.Query.Internal.SqlServerQueryModelVisitor.VisitQueryModel(QueryModel queryModel)
   at Microsoft.EntityFrameworkCore.Query.EntityQueryModelVisitor.CreateQueryExecutor[TResult](QueryModel queryModel)
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.CompileQueryCore[TResult](Expression query, INodeTypeProvider nodeTypeProvider, IDatabase database, ILogger logger, Type contextType)
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.<>c__DisplayClass19_0`1.<CompileQuery>b__0()
   at Microsoft.EntityFrameworkCore.Query.Internal.CompiledQueryCache.GetOrAddQueryCore[TFunc](Object cacheKey, Func`1 compiler)
   at Microsoft.EntityFrameworkCore.Query.Internal.QueryCompiler.Execute[TResult](Expression query)
   at Remotion.Linq.QueryableBase`1.GetEnumerator()
   at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
   at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
   at MyCode.MyRepository.<>c__DisplayClass1_0.<GetDistinctLibraryManagerShelves>b__0(MyDbContext db) in C:\src\MyCode\MyRepository.cs:line 63