Node disappears when animating a Tween with duration of 0

[danielzting]

Godot version:

v.3.2.2.stable.official

OS/device including version:

macOS Catalina 10.15.5 (19F101)
MacBook Air (Retina, 13-inch, 2018)
Intel UHD Graphics 617 1536 MB
Confirmed on both GLES2 and GLES3

Issue description:

Animating a node with a tween with a duration of 0 causes the node to disappear. I expected it to just animate instantly.

Steps to reproduce:

1. Add ColorRect
2. Add Tween and Timer under ColorRect
3. Set Timer to One Shot and Autostart
4. Attach script to ColorRect
5. Connect Timer timeout() signal to the following code:

extends ColorRect

func _on_Timer_timeout():
    $Tween.interpolate_property(self, "rect_position", null, Vector2(100, 100), 0)
    $Tween.start()

6. Play scene

Minimal reproduction project:

tween.zip

[KoBeWi]

Still valid in 60dcc4f
Might be some bug with interpolaters. The easiest fix would be a special case for 0 time interpolation.