Fix incorrect nullity check.
Fix incorrect nullity check.

(cherry picked from commit 1fa4aad09e09af260d0283dca038e96230580031)

Conflicts:
	MoreLinq/Split.cs

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