New trace when added to the already used port having net_label, throws render error

[imrishabh18]

The motor driver fails to render now, cause that port is already having the net_label and rather that using the same net_label, it just throws render error.

My hunch is that this bug was introduced in this PR probably - #422

cc: @Abse2001 @seveibar Should we revert this PR? Meanwhile Abse can take a look at this issue

[Abse2001]

@imrishabh18 Yeah I know the problem and Im working on a fix

[Abse2001]

@imrishabh18 The problem is that when the trace complexity changes a trace into a label, it does not take into account the label rule that no label should render above another label. So the error is legit, but we should handle this differently.