inference: relax isbrokensubtype for egal objects

Author: vtjnash

base/compiler/typeutils.jl

@@ -41,7 +41,7 @@ end
 # some of these queries, this check can be used to somewhat protect against making incorrect
 # decisions based on incorrect subtyping. Note that this check, itself, is broken for
 # certain combinations of `a` and `b` where one/both isa/are `Union`/`UnionAll` type(s)s.
-isnotbrokensubtype(@nospecialize(a), @nospecialize(b)) = (!iskindtype(b) || !isType(a) || hasuniquerep(a.parameters[1]))
+isnotbrokensubtype(@nospecialize(a), @nospecialize(b)) = (!iskindtype(b) || !isType(a) || hasuniquerep(a.parameters[1]) || b <: a)
 
 argtypes_to_type(argtypes::Array{Any,1}) = Tuple{anymap(widenconst, argtypes)...}