"sibling" Qml files that import the same Url-loaded module fail to load

This is somewhat hard to explain, but if you have a file structure like this:

main.qml
  uses Bug
  uses Zub
Bug.qml
  imports foo
Zub.qml
  imports foo

foo is a module imported from http://...

Bug.qml will fail to load with:

file:///C:/Users/josh/scratch/qt/qtbug-xxxxx/main.qml:7:3: Type Bug unavailable
       Bug {
       ^
file:///C:/Users/josh/scratch/qt/qtbug-xxxxx/Bug.qml:2:1: module "foo" is not installed
     import foo 1.0
     ^

If you do any of the following:
1) Add "import foo 1.0" to main.qml
2) Remove Bug from use in main.qml
3) Remove Zub from use in main.qml

Everything works fine.

Internally this seems to be because the two QQmlTypeLoader::Blob objects share a QQmlQmldirData object, but they don't expect to be doing so, and their use of the Import and priority on QQmlQmldirData conflicts.