fix #10165, which gives wrong method for eltype(AbstractArray{Int})

regression watch: this is a risky commit. seems crazy, but all the tests
pass so let's see what happens.

this really needs #8974 to be fixed properly

src/jltypes.c

@@ -149,11 +149,8 @@ int jl_is_leaf_type(jl_value_t *v)
 {
     if (jl_is_datatype(v)) {
         if (((jl_datatype_t*)v)->abstract) {
-            if (jl_is_type_type(v)) {
-                jl_value_t *tp0 = jl_tparam0(v);
-                return (jl_is_datatype(tp0) && is_unspec((jl_datatype_t*)tp0)) ||
-                    !jl_has_typevars_(tp0,1);
-            }
+            if (jl_is_type_type(v))
+                return !jl_is_typevar(jl_tparam0(v));
             return 0;
         }
         jl_tuple_t *t = ((jl_datatype_t*)v)->parameters;

test/reflection.jl

@@ -69,3 +69,9 @@ end
 @test isbits(Float32)
 @test isbits(Int)
 @test !isbits(AbstractString)
+
+# issue #10165
+i10165(::DataType) = 0
+i10165{T,n}(::Type{AbstractArray{T,n}}) = 1
+@test i10165(AbstractArray{Int}) == 0
+@test which(i10165, (Type{AbstractArray{Int}},)).sig == (DataType,)