Set intersection = 1 during intersect_sub_datatype (#46882)

(cherry picked from commit e6d9979)

Author: N5N3

src/subtype.c

@@ -2780,7 +2780,7 @@ static jl_value_t *intersect_sub_datatype(jl_datatype_t *xd, jl_datatype_t *yd,
         JL_GC_PUSHARGS(env, envsz);
         jl_stenv_t tempe;
         init_stenv(&tempe, env, envsz);
-        tempe.ignore_free = 1;
+        tempe.intersection = tempe.ignore_free = 1;
         if (subtype_in_env(isuper, super_pattern, &tempe)) {
             jl_value_t *wr = wrapper;
             int i;

test/subtype.jl

@@ -1885,3 +1885,10 @@ let A = Tuple{Array{Pair{T, JT} where JT<:Ref{T}, 1} where T, Vector},
     @test_broken I <: A
     @test_broken !Base.has_free_typevars(I)
 end
+
+#issue #46871
+struct A46871{T, N, M} <: AbstractArray{T, N} end
+struct B46871{T, N} <: Ref{A46871{T, N, N}} end
+for T in (B46871{Int, N} where {N}, B46871{Int}) # intentional duplication
+    @testintersect(T, Ref{<:AbstractArray{<:Real, 3}}, B46871{Int, 3})
+end