Bug: orphand detected when a signal is between 2 pins of the same chip

[fdeprey]

'MUXNAH': {'U901AH': '27'},
'MUXNAL': {'U901AL': '27'},
'MUXPAH': {'U901AH': '25'},
'MUXPAL': {'U901AL': '25'},
rug2_2.F.1.NET.zip

[GeoffreyBultot]

@fdeprey
fixed by #5