Help with build failure (updating mercurial)

[Neal Becker]

gmane.linux.network.networkmanager.devel
http://koji.fedoraproject.org/koji/taskinfo?taskID=662698
...
error: File must begin with "/": unset
error: File must begin with "/": DISPLAY
Checking for unpackaged
file(s): /usr/lib/rpm/check-files /var/tmp/mercurial-1.0.1-3.fc10-root
RPM build errors:
    File must begin with "/": unset
    File must begin with "/": DISPLAY

What's causing this?

I also tried to reproduce this locally, but running make mockbuild, but I
only got an empty build log.