Blender Git Loki

Fix #19802: tweaking the values of e.g. the add tube operator when
entering editmode on a second mesh would create a duplicate tube.

Cleaning the undo stack from the previous mesh would mess up the redo.
Also, OBJECT_OT_mode_set was causing enter/exit editmode undo push to
be done twice, now it leaves undo push to the operator it calls.