Seemingly needless error CS0121: The call is ambiguous between the following methods or properties: 'x(Action)' and 'x(Func<Task>)'

[sandersaares]

Version Used:
VS 2015 Update 3

Steps to Reproduce:

Attempt to compile the following code:

private void x()
{
}

private void yyyyyyyyyyyyyyy(Action a)
{
}

private void yyyyyyyyyyyyyyy(Func<Task> a)
{
}

private void z()
{
	yyyyyyyyyyyyyyy(x);
}

Expected Behavior:

Code compiles and the Action overload is used in z().

Actual Behavior:

CS0121: The call is ambiguous between the following methods or properties: 'foo.yyyyyyyyyyyyyyy(Action)' and 'foo.yyyyyyyyyyyyyyy(Func)'

Further notes:

Explicitly casting it as yyyyyyyyyyyyyyy((Action)x); works fine.

Casting as yyyyyyyyyyyyyyy((Func<Task>)x); is a compile error.

[gafter]

This is bullet 3 in #250