Change of background color when zooming in on RGBA images

[maxime915]

The following screenshot shows an RGBA image where the black background has an alpha of 0.

When zooming in, the background changes to white.

I have also tried to disable the Digital Zoom, the issue persists.
Although this is shown on the ULiège instance, the bug was reproduced by Ba Thien on another instance.
I can send the image (<100kB), if needed to reproduce of the bug.