Categorized SingleOrFallback tests.
Categorized SingleOrFallback tests.

ddpruitt/morelinq,morelinq/MoreLINQ,fsateler/MoreLINQ,Agbar/MoreLINQ,morelinq/MoreLINQ,Agbar/MoreLINQ,fsateler/MoreLINQ,ddpruitt/morelinq,smzinovyev/MoreLINQ