fix #22908, typemap ordering of Union vs. Type{Union{...}}.

Ref #22909
(cherry picked from commit 7e37e5d)

Author: JeffBezanson

src/typemap.c

@@ -1045,6 +1045,8 @@ jl_typemap_entry_t *jl_typemap_insert(union jl_typemap_t *cache, jl_value_t *par
             newrec->isleafsig = 0; // Type{} may have a higher priority than DataType
         else if (decl == (jl_value_t*)jl_unionall_type)
             newrec->isleafsig = 0; // Type{} may have a higher priority than UnionAll
+        else if (decl == (jl_value_t*)jl_uniontype_type)
+            newrec->isleafsig = 0; // Type{} may have a higher priority than Union
         else if (jl_is_type_type(decl))
             newrec->isleafsig = 0; // Type{} may need special processing to compute the match
         else if (jl_is_vararg_type(decl))

test/specificity.jl

@@ -172,3 +172,8 @@ let A = Tuple{T, Array{T, 1}} where T,
     @test args_morespecific(C, B)
     @test args_morespecific(C, A)
 end
+
+# issue #22908
+f22908(::Union) = 2
+f22908(::Type{Union{Int, Float32}}) = 1
+@test f22908(Union{Int, Float32}) == 1