Regression, VBox 4.3.12 guest additions can not longer be installed in safe mode "Failed to calculate strong name"

I tested 0.4.15-dev-2569-g9f549db gcc 8.4.0 dbg win.
This test has been done on a computer without VT-x extensions.

Reproduction steps

• use VirtualBox 4.3.12, other versions might reproduce the issue as well, but 4.3.12 is what I tested
• (VBox 5.1.x and 6.0.x do still offer that feature)
• DO NOT USE VBOX 6.1 TO TEST AS IT LACKS THAT FEATURE 3D GRAPHICS
• Enable 3D support in graphics settings
• Install ROS
• After graphical setup, boot to safe mode and install VBox Additions with "Direct3D" support enabled.

Expected result
The setup should complete
The last time that my notes proved me performing that sequence successfully was with:
0.4.14-RC-36-gb30846a (gcc4.7.2 win) and
0.4.15-dev-730-gabbe656 (built gcc win, but I don't remember the version)
reactos-bootcd-0.4.15-dev-2069-gfd8080b-x86-gcc-lin-dbg_STILL_OK.webm

Observed result
The setup fails and the screenshot shows something about "Failed to calculate strong name"
0.4.15-dev-2569-g9f549db_guestAdditionsFailed.png
0.4.15-dev-2569-g9f549db_guestAdditionsFailed.log

The bugs reproducibility is not 100%, it happens maybe on 33% of the tries for me for the affected builds! May be a race condition.