Goal:
  
  A : Type
  B : Type
  p : A → B → bool
  x : A
  y : B
  l : list A
  l' : list B
  r : is_true (p x y)
  X : All2 (λ (x : A) (y : B), p x y) l l'
  IHX : is_true (forallb2 p l l')
  ============================
   (is_true (p x y && forallb2 p l l'))


DEBUG:Going to execute:
<coq-core.plugins.ssreflect::ssrrewrite@0> $1 $2
Level 0: Backtrace:

Tactic failure: congruence failed.
Level 0: Backtrace:

Tactic failure: congruence failed.