Since "upgrading" to 1.4 unionfs on my pc532 has gone from "a bit
flakey" to "unuseable".  With a configuration which I used extensively
with never a panic in the past I now get a pretty much guaranteed
panic with "union: missing upper layer in write".

I suppose I should put in a send-pr, but then I know unionfs is generally
only considered half working anyway. What has changed to make it worse?

The configuration I have is to have one tree with the netbsd source
distribution mounted below a tree I use to build in and for local
modifications. Now if I go and make something in the upper layer I may
have several panics before I finish.

Ian