Get all but last from a sequence

public static IEnumerable<T> AllButLast<T>(this IEnumerable<T> input)
{
	var next = input.First();
	foreach(var item in input.Skip(1))
	{
		yield return next;
		next = item;
	}
}

alternative that only starts the iteration once:

public static IEnumerable<T> AllButLast<T>(this IEnumerable<T> input)
{
	bool haveNext = false;
	var next = default(T);
	foreach (var item in input)
	{
		if (!haveNext)
		{
			haveNext = true;
			next = item;
			continue;
		}
		yield return next;
		next = item;
	}
}