Wire creation problem

Hello
I tried this in Test Harness, basically create
a rectangle.

line L1 0 0 0 1 0 0
trim L1 L1 0 10
line L2 0 5 0 1 0 0
trim L2 L2 0 10
line L3 0 0 0 0 1 0
trim L3 L3 0 5
line L4 10 0 0 0 1 0
trim L4 L4 0 5
mkedge e1 L1
mkedge e2 L2
mkedge e3 L3
mkedge e4 L4
wire w e1 e2 e3 e4
dump w
#mkoffset o w 1

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It shows it has only THREE edges, not FOUR
why is it ?
U can see if mkoffset is done, it offsets 3 edges only.
Is it a bug ?

thanks and regards

- Prasad