A greater mystery I now face is if I compile this from the command line, before and after my patch:
```
abstract class A[T] {
  val foo: Set[_ <: T] = null
  val bar: Set[_ <: T]
}
```
with ```scalac -Xprint:patmat -Yrangepos -Xprint-pos -Yshow-trees```
I get ```<18>``` as the position in both cases. The only difference in the tree comes later, at the expected point.
```diff
         [-[63:74]<tpt>-]{+[63]<tpt>+} // tree.tpe=Set[_ <: T]
```