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This fixes a bug related to:
http://www.freecadweb.org/tracker/view.php?id=2093
that during creation of a geometric element if a vertical/horiz autoconstraint is to be enforced, it is not enforced if the endpoints of the geometric element under creation are
coincident with external geometry.
According to the discussion here:
http://forum.freecadweb.org/viewtopic.php?f=10&t=12254&sid=eacf5bdee068cb71cc54dc5a62a6849d&start=20#p99359
this fixes the bug.
It does not fulfil the request on the ticket as it was decided to still allow an explicit addition of a vertical/horizontal constraint, as
it may be needed in some cases and the user expects to be able to add them, even if it will lead to an overconstrained sketch.
How to reproduce?
1. Create a rectange
2. Pad it
3. Create a new sketch on a face
4. link two corners as "external geometry" (but not the ones of a diagonal)
5. Create a line coincident with the first and second corners, so that the line is horizontal or vertical
In master it will force horiz or vert leading to a overconstrained sketch.
With this patch, the horiz/vert will not be enforced in this case.