Blender Git Loki

Work around T86015: Crash undoing in certain scenario (disabling Global Undo).

Simply disable advanced 're-use current blend data` process when loading
a memfile step and Global Undo is disabled, since there is no way to
ensure we have a proper 'differential' state in the stack then.

NOTE: this is a quick work-around to fix the crash, not a satisfying
solution by far (pretty sure there can still be crashes if you then
re-enable Global Undo afterwards e.g.).