[2.0.73] Wrong modules applied when force-stamping assembler 3 over assembler 2

[thuejk]

When force-upgrading an assembler 2 to assembler 3, the modules are sometimes not correctly applied. If the target assembler 3 of the force print has 4 modules, it sometimes happens that only 2 modules are inserted.

There seems to be a random element to this bug. In the attached video, I force blueprint 3 times, but the bug only happens once. I can't see any pattern for when the bug happens or doesn't happen.

Undo is also broken, as also demonstrated in the video. The leftmost assembler ends up missing its original modules, after the undo.

This bug also happened in version 2.0.72, i.e. was likely not recently introduced.