Goal:
  
  G : t
  s : VSet.t
  x : V.t
  p : SPath G s x x
  y : VSet.elt
  yinp : VSet.In y (snodes G p)
  rx := spath_refl G VSet.empty x : SPath G VSet.empty x x
  disj : Disjoint s VSet.empty
  c : SPath G (VSet.union s VSet.empty) y y
  wc : sweight c = sweight p + sweight rx
  ============================
   (exists c : SPath G s y y, sweight c = sweight p)


DEBUG:Going to execute:
<coq-core.plugins.ltac::unshelve@0> $1
DEBUG LTAC Evaluated term: (reroot_spath_aux G s x x p y yinp VSet.empty rx
                              disj)