NodePath in built-in node properties is invalid after moving/renaming node

[pouleyKetchoupp]

Godot version

3.3.2.stable, 4.0.dev (92f20fd)

System information

Windows 10

Issue description

NodePath properties are kept up-to-date in the editor when the path changes for script export variables, but not for built-in nodes (for example bodies in physics joints).

Steps to reproduce

Using the minimal reproduction project:

1. Open the project in the editor
2. Select Spatial6/PinJoint node in the tree
3. Observe the path for node_a property: ../RigidBody (which is correct)
4. Move RigidBody node as a child of PinJoint node
5. Select Spatial6/PinJoint node again
6. Observe the path for node_a property: ../RigidBody (now incorrect)

The same thing happens with RemoteTransform, or any other built-in node using a NodePath property.

Minimal reproduction project

3.x version:
NodePathBug.zip

4.0 version:
NodePathBug-4.0.zip