Sketcher B-splines hate symmetry and/or tangent about freecad

[krushia]

Tried to use the "Sketcher_JoinCurves" tool to make the same geometry, and ended up with the error <class 'ValueError'>: Connecting the end points of the same curve is not yet supported.

I wonder if that sums up the core issue, which would what #12653 is about. In that case, this bug should maybe be titled "Sketcher doesn't warn about unsupported loops of curves in all cases"?

[maxwxyz]

@AjinkyaDahale this seems exactly like #12653 can you confirm?

[AjinkyaDahale]

Probably a generalization: in #12653 the issue is related to a B-spline being end to end tangent with itself. Here, an extra arc is added.