Unexpected type errors when wrapping a generic function type

Not really sure how to title this more clearly, but here's the repro. Sorry if there's something obvious I'm missing here.

https://flow.org/try/#0PTAEAEDMBsHsHcBQiAuBPADgU1AESwM4DGATgJYYqwkA8AKgHygC8oA3gL4DcqmOAMrACGAEywj8xcpWot23RJACuAOyIoysFaHgkhGGgEESAcwYAKSCoBcoYyZZMAbrDIiAlLfuPQLt+0RQUBIsFCUSbSseDmRlNQ0tUDhRACEhAjIiegtYACMAK1tJUgoqWkZPX1cReWQiLQIUJOERAHU9DGwa1l19c2SRNIyidx4g8fHFVXVNbQHs8zzCvEISmXKGdwCJgfb9LsWC0dAQUCwSEmoCQPGBoczD-OPT+GoAa2uYoA

```
type Descriptor = {};
type LoadedDescriptor = {};
function wrap(fn: Arg => void): Arg => void {
return fn;
}

function loadBasic(obj: Descriptor): void {}

const loadWrapped = wrap(loadBasic);

function load(obj: Descriptor) {
loadWrapped(obj); // errors
loadBasic(obj); // works
}
```
resulting in
```
11: const loadWrapped = wrap(loadBasic);
^ function. This type is incompatible with the expected param type of
5: function wrap(fn: Arg => void): Arg => void {
^ function type
This parameter is incompatible:
14: loadWrapped(obj); // errors
^ type application of polymorphic type: Descriptor. Has some incompatible type argument with
9: function loadBasic(obj: Descriptor): void {}
^ type application of polymorphic type: Descriptor
Type argument `T` is incompatible:
13: function load(obj: Descriptor) {
^ T. This type is incompatible with
13: function load(obj: Descriptor) {
^ some incompatible instantiation of `T`
```

It certainly seems like Flow should be able to see that the input type is the same for both.

It works if the wrapper is

```
function wrap(fn: Fn): Fn {
```
but this is a trimmed down example. In my case I'm explicitly using a function because I'm adding an additional parameter.