Possible Resharper's bug

TestResharper.vb

Public Sub TestResharper1()
    Dim source As String = "0123456789"
    Dim lengths = New Integer() {4}.ToList()

    lengths.ForEach(
        Sub(x)
            source = source.Substring(0, x) 'Resharper warning: Value assigned is not used in any execution path
        End Sub)

    Debug.WriteLine(source) '0123
End Sub

Public Sub TestResharper2()
    Dim source As String = "0123456789"
    Dim lengths = New Integer() {4}.ToList()

    lengths.ForEach(
        Sub(x) source = source.Substring(0, x)) 'No Resharper warning

    Debug.WriteLine(source) '0123
End Sub