ID 376881 - Using the FIRST Undo on a Clone Stamp causes a Black Bakeable rectangle to appear on the model

Problem summary
When using the clone stamp, if the user Undo's the Clone Stamp, a Black Rectangle appears within the paint buffer.

This Black Rectangle is "Bakeable" which can cause black areas on the user's model.

The Error only happens on the first undo while on clone stamp. 
If you undo first in basic brush, the black rectangle doesn't appear.

The black rectangle appears over whatever area the clone stamp paint covered (doesn't go over basic paint, even if it's also in the paint buffer).

You can bake this black rectangle from the paint buffer onto the geo. 
If you undo and then there's nothing left in the paint buffer, you can move the view and the black rectangle stays in place (since it doesn't auto bake on view move).

 

Screenshot Reference:

Customer reported platform
ubuntu

Steps to reproduce

1) Open Mari

2) Open a project with a texture ( e.g the example face project )

3) Use the Clone Tool from the toolbar to clone part of the model

4) Undo the Clone with Ctrl+Z

Result 1: The Cloned area should now be a BLACK RECTANGLE

5) Using the Clone Tool, Clone and paint from the black area

Result 2: Other parts of the model will used the Black rectangle for their new look

Workaround
Undo ANYTHING else beforehand  ( e.g draw one line of the Paint Brush and Undo it ) 

Reproduced by support

This bug has been reproduced in:
Mari4.2v1- Windows 7
Mari4.1v1 - Windows 7
Mari4.0v1 - Windows 7
Mari3.4v1 - Windows 7
Mari3.3v1- Windows 7 - regression

Unable to reproduce bug in:
Mari3.2v1 - Windows 7


Earliest version tested
- This issue no longer appears in this version and has regressed

Expected behaviour
Undo should return the look before the action.

Actual behaviour
Undo causes a BLACK RECTANGLE to appear on the cloned area.