Segment fault cause by Base.convert returning wrong type

[dlfivefifty]

An overloaded convert routine that returns the wrong type causes a segment fault in 0.4 but in 0.3 correctly throws the error

ERROR: type: bar: in typeassert, expected Foo, got Float64
 in bar at none:5

Here is an example:

 immutable Foo
   x::Int
end

function bar(x)
   y::Foo
   y=x
end

Base.convert(::Type{Foo},x::Int) = float(x)

bar(1)