Diablo II shareware crashes with Wine assertion when run in fullscreen mode

Diablo II shareware from rapps
VBox 4.3.12 + VBEMP + inbuilt Mesa

"0.4.12-dev-392-gc3e4b5f gcc dbg win" starts Diablo II fine without crashing when run with cmdline-param -w to start windowed. Even the palette is 100% perfect like on WinXP then.

"0.4.12-dev-392-gc3e4b5f gcc dbg win" starting Diablo II without any cmdline will try to start in fullscreen and crashes with an assertion like in picture
0.4.12-dev-392-gc3e4b5f__d2.png
0.4.12-dev-392-gc3e4b5f__d2.log

This is known to be a regression and already happened mid2018. I now opened a ticket (issue is hidden in our official releases because I use to sledgehammer-revert WineD3D in there atm). It was introduced by some Wine-D3D-sync.

0.4.12-dev-392-gc3e4b5f already contains latest Mesa downgrade to 2.6. Mesa downgrade did not introduce this, but also did not help.