Fix thinko in swapping junction in Junction ~ Junction
Fix thinko in swapping junction in Junction ~ Junction

As spotted in
  https://stackoverflow.com/questions/51254830/double-junction-arguments-swapping-sides

Since the joining is done from the left, we shouldn't swap the eigenstates
as well.  Feels that there should be a better solution, but I cannot think
of it now.

Fixes R#2042

labster/rakudo,tony-o/rakudo,tbrowder/rakudo,nbrown/rakudo,tony-o/rakudo,tbrowder/rakudo,salortiz/rakudo,MasterDuke17/rakudo,rakudo/rakudo,Gnouc/rakudo,tony-o/rakudo,labster/rakudo,salortiz/rakudo,labster/rakudo,Gnouc/rakudo,salortiz/rakudo,nbrown/rakudo,tbrowder/rakudo,tony-o/rakudo,softmoth/rakudo,tbrowder/rakudo,salortiz/rakudo,tbrowder/rakudo,rakudo/rakudo,rakudo/rakudo,rakudo/rakudo,rakudo/rakudo,nbrown/rakudo,labster/rakudo,Gnouc/rakudo,tony-o/rakudo,Gnouc/rakudo,nbrown/rakudo,nbrown/rakudo,softmoth/rakudo,salortiz/rakudo,MasterDuke17/rakudo,Gnouc/rakudo,MasterDuke17/rakudo,MasterDuke17/rakudo,tbrowder/rakudo,labster/rakudo,MasterDuke17/rakudo,Gnouc/rakudo,softmoth/rakudo,rakudo/rakudo,tony-o/rakudo,softmoth/rakudo,nbrown/rakudo,salortiz/rakudo,labster/rakudo,softmoth/rakudo,MasterDuke17/rakudo