Inserting same node twice in LinkedList triggers infinite loop

I am trying to understand why does inserting the same node twice in a singly linked list causes an infinite loop.

I tried to insert the last node as the new head node. But when I run the code, it's starting an infinite loop I can see since I am calling a method to print nodes at the end. Here's my code.

class Node:
    def __init__(self, data):
        self.data = data
        self.next = None


class LinkedList:
    def __init__(self):
        self.head = None

    def insertLast(self, newNode):
        if self.head is None:
            self.head = newNode
        else:
            lastNode = self.head
            while True:
                if lastNode.next is None:
                    break
                lastNode = lastNode.next
            lastNode.next = newNode

    def insertHead(self, newNode):
        # x, y ,z. => new head, x,y,z
        if self.head is None:
            print("List is empy please call inserlast()")
        else:

            currentHead = self.head
            self.head = newNode
            self.head.next = currentHead

    def printList(self):
        if self.head is None:
            print("EMPTY List. No Data found!")
            return
        else:
            currentNode = self.head
            while True:
                print(currentNode.data)
                currentNode = currentNode.next
                if currentNode is None:
                    break


node1 = Node("Head")
node2 = Node("Some Data")
node3 = Node("Some More Data")

# I am adding this node at the end of the list
newnode1 = Node("New Head")

linkedList = LinkedList()

# create a new linked list by inserting at end
linkedList.insertLast(node1)
linkedList.insertLast(node2)
linkedList.insertLast(newnode1)

# using a node i have already added in the list as New head of the list
linkedList.insertHead(newnode1)
linkedList.printList()