more conservative promote_rule for Some (#58836)

Author: adienes

base/some.jl

@@ -14,8 +14,6 @@ end
 
 Some(::Type{T}) where {T} = Some{Type{T}}(T)
 
-promote_rule(::Type{Some{T}}, ::Type{Some{S}}) where {T, S<:T} = Some{T}
-
 nonnothingtype(@nospecialize(T::Type)) = typesplit(T, Nothing)
 promote_rule(T::Type{Nothing}, S::Type) = Union{S, Nothing}
 function promote_rule(T::Type{>:Nothing}, S::Type)

test/some.jl

@@ -3,7 +3,7 @@
 ## promote()
 
 @test promote_type(Some{Int}, Some{Float64}) == Some
-@test promote_type(Some{Int}, Some{Real}) == Some{Real}
+@test promote_type(Some{Int}, Some{Real}) == Some
 @test promote_type(Some{Int}, Nothing) == Union{Some{Int},Nothing}
 
 ## convert()