Weird behavior with getproperty

what.jl

julia> struct Wrapper
                  dict::Dict{Symbol, Any}
              end

julia> Base.getproperty(w::Wrapper, k::Symbol) = get!(getfield(w, :dict), k, Wrapper(Dict{Symbol,Any}()))

julia> Base.setproperty!(w::Wrapper, k::Symbol, val) = setindex!(getfield(w, :dict), val, k)

julia> w = Wrapper(Dict())
Wrapper(Dict{Symbol, Any}())

julia> w.f = () -> 1
#3 (generic function with 1 method)

julia> w.f() = 5
WARNING: Method definition #3() in module Main at REPL[5]:1 overwritten at REPL[6]:1.

julia> w.f2() = 6

julia> w.f()
5

julia> w.f2()
6

julia> w() # how did this happen?
6