Sketcher: Fix equality constraint command
Sketcher: Fix equality constraint command

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For select constraint then click elements mode.

Fixes:
https://forum.freecadweb.org/viewtopic.php?f=10&t=51716&p=458207#p457974

Fat-Zer/FreeCAD_sf_master,Fat-Zer/FreeCAD_sf_master,Fat-Zer/FreeCAD_sf_master,Fat-Zer/FreeCAD_sf_master,Fat-Zer/FreeCAD_sf_master