Having BoneAttachment node before a Physical Bone for the same bone throws error

[Miziziziz]

Godot version: 3.2.2 stable

OS/device including version: Windows 10

Issue description:

having a bone attachment node attached to a non root bone before a physical bone for that same bone in the heirarchy as shown:

throws this error message:
scene/3d/skeleton.cpp:637 - Condition "bones[p_bone].physical_bone" is true.
./core/list.h:158 - Condition "!p_I" is true. Returned: false

and this error message when run:
E 0:00:00.501 erase: Condition "!p_I" is true. Returned: false
<C++ Source> ./core/list.h:158 @ erase()
everything works fine, but you get that error message for each bone on scene load

But if you rearrange it this way it works fine with no error message:

Minimal reproduction project:

boneerrormessagedemonstration.zip
project contains two scenes: HasErrorMessage.tscn and NoErrorMessage.tscn, which show it not working correctly and it working correctly respectively

[dane-johnson]

I think attaching a BoneAttachment might actually un-parent the Physical Bones. I keep finding their collision shapes at the world origin.

[pouleyKetchoupp]

Can still reproduce in 3.2.4 beta 5.

[akien-mga]

Fixed by #67698.