simple-damage: fix --rotating-transform

When the flag --rotating-transform is set, the client changes
the whole content of the buffer. Still, only the area with
the ball get damaged, leading to heavy glitches.
1 job from master in 5 minutes and 17 seconds (queued for 1 minute and 4 seconds)
Status Job ID Name Coverage
  Build
passed #39062
build-native

00:05:17