diskless/rm causing deadlock?

I stumbled on this in -current, but it's also true for 6.2.
/(root) is mounted diskless, doing rm of a file in /, even as a lowly mortal
will hang the network, and hence everything.
on a 6.1 system, it works as expected.

badwolf> rm /usr/ports
rm: /usr/ports: Read-only file system

i'll try to hunt this down, but some pointers where to start might be
helpfull

danny