pkg_rolling-replace infinite loop?

[Ian D. Leroux <idleroux%fastmail.fm@localhost>]

For the last twelve hours or so pkg_rolling-replace -u has been
rebuilding and reinstalling wl-snapshot over and over again (after
successfully updating most of the other packages on my system).  The
installation seems to complete successfully every time, and then
pkg_rr just selects wl-snapshot as the next package to update, again.

I've checked that /var/db/pkg/wl-2.15.6.20090322nb1 contains no
+INSTALLED_INFO file and no mention of the word unsafe or UNSAFE, so I
don't think it's being marked unsafe_depends, and of course
pkg_chk -uq doesn't report it as being out of date (after all, it's
been updated a few dozen times by now).

I updated my pkgsrc tree from cvs again this morning (so somewhere
around noon GMT) and restarted pkg_rr, the behaviour is the same.

This is all on NetBSD/amd64 5.0.2

Any ideas on where I should start looking for an explanation?

Cyclically yours,

Ian Leroux