Commit
45b7d0126b82c2bdefeb80ebb2b6b9b41a84789b
by laforgecommands.py: Resolve possible variable use before assignment
pySim/commands.py:223:18: E0606: Possibly using variable 'skip' before assignment (possibly-used-before-assignment)
Let's raise an exception in the erroneous case.
Change-Id: Id1a892c3446e472699e77f076c2414277e92c98d