Type inference fails for `@distributed for` but not for `mapreduce`

In some cases, type inference works for mapreduce but fails for @distributed for.

function foo()
    A = Array{Float64}(undef, 10)
    result = @distributed (+) for _ in 1:100
        rand!(A)
        sum(A)
    end
end

function bar()
    A = Array{Float64}(undef, 10)
    result = mapreduce(+, 1:100) do _
        rand!(A)
        sum(A)
    end
end

julia> @code_warntype foo()
Variables
  #self#::Core.Const(foo)
  JuliaLang/julia#272::var"#272#273"{Vector{Float64}}
  result::Any
  A::Vector{Float64}

Body::Any
1 ─ %1 = Core.apply_type(Main.Array, Main.Float64)::Core.Const(Array{Float64, N} where N)
│        (A = (%1)(Main.undef, 10))
│   %3 = Main.:(var"#272#273")::Core.Const(var"#272#273")
│   %4 = Core.typeof(A)::Core.Const(Vector{Float64})
│   %5 = Core.apply_type(%3, %4)::Core.Const(var"#272#273"{Vector{Float64}})
│        (#272 = %new(%5, A))
│   %7 = JuliaLang/julia#272::var"#272#273"{Vector{Float64}}
│   %8 = (1:100)::Core.Const(1:100)
│   %9 = Distributed.preduce(Main.:+, %7, %8)::Any
│        (result = %9)
└──      return %9

julia> @code_warntype bar()
Variables
  #self#::Core.Const(bar)
  JuliaLang/julia#274::var"#274#275"{Vector{Float64}}
  result::Float64
  A::Vector{Float64}

Body::Float64
1 ─ %1 = Core.apply_type(Main.Array, Main.Float64)::Core.Const(Array{Float64, N} where N)
│        (A = (%1)(Main.undef, 10))
│   %3 = Main.:(var"#274#275")::Core.Const(var"#274#275")
│   %4 = Core.typeof(A)::Core.Const(Vector{Float64})
│   %5 = Core.apply_type(%3, %4)::Core.Const(var"#274#275"{Vector{Float64}})
│        (#274 = %new(%5, A))
│   %7 = JuliaLang/julia#274::var"#274#275"{Vector{Float64}}
│   %8 = (1:100)::Core.Const(1:100)
│   %9 = Main.mapreduce(%7, Main.:+, %8)::Float64
│        (result = %9)
└──      return %9

Reproduce the issue with the foo and bar examples in the report, then compare their @code_warntype output. Start by tracing the @distributed for path through Distributed.preduce and contrast it with mapreduce. Done means the distributed example no longer produces an Any result when the equivalent mapreduce inference is Float64.