Goal:
  
  A : Type
  B : Type
  p : A → B → bool
  a : A
  l : list A
  b : B
  l' : list B
  q : list A
  q' : list B
  IHl : ∀ l' : list B,
          forallb2 p l l' && forallb2 p q q' → forallb2 p (l ++ q) (l' ++ q')
  ============================
   (p a b && forallb2 p l l' && forallb2 p q q'
    → p a b && forallb2 p (l ++ q) (l' ++ q'))


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

Tactic failure: congruence failed.
Level 0: Backtrace:

Tactic failure: congruence failed.