Paint: bucket color wrong when mixing colors

[godiard]

Steps to reproduce:

• Select the pencil.
• Open the color palette, select a color, and modify it dragging the reed/green/blue to get a color different to any other in the pre selected values.
• Change the size to select a bigger value.
• Draw a closed shape
• Select the bucket
• Paint the area inside the shape

Result: the area painted by the bucket have a different color than the trace painted by the brush, and should be equal.

This issue do not happen with the pre selected colors.

Tested on Paint >=58

[godiard]

Fixed by 18726b28d0286640d887d5dfe9e74a0972bc1bd0