"rpm-ostree db version" is busted

```
# rpm-ostree rpm version 1d4c0bf
(rpm-ostree 2014.109 rpm:15612): GLib-WARNING **: GError set over the top of a previous GError or uninitialized memory.
This indicates a bug in someone's code. You must ensure an error is NULL before it's set.
The overwriting error message was: No such file or directory: /var/lib

(... snipped: this warning repeated many many times ...)

ostree commit: 1d4c0bf (1d4c0bf26f1d4dbc179e0baeced16c3a141a5938fe0dada414af3039e16e56fc)
  rpmdbv is:                         354:dfc6707e046a6797da96be6c565f50264f17b1cf
error: No such file or directory: /var/lib
```