[Puppet Users] facter --yaml leaves some fields blank

Sometimes "facter --yaml" doesn't list all the values specified on the
command line. I can't find rhyme nor reason why. Here's a demo to
show what I mean:

# facter --version
1.5.7

# facter --yaml fqdn macaddress lsbdistcodename
---
fqdn: my.host.name.example.com
lsbdistcodename: squeeze
macaddress: "00:00:00:00:00:00"

We had been using the above command for a while to extract values for
a shell script. However we recently discovered that when we have a
Linux box who's primary NIC is "br123" (a bridge device) that the
macaddress fact shows up as "all zeros" like above. (I consider this a
bug but... that's not the point). Luckily macaddress_eth0 shows the
real MAC address no matter what. Therefore, we made the simple code
change to use the macaddress_eth0 fact instead. However now facter
goes silent on most of the values:

# facter --yaml fqdn macaddress_eth0 lsbdistcodename
---
fqdn: my.host.name.example.com
macaddress_eth0:
lsbdistcodename:

This seems to be just related to facts on the command line. If I do a
plain "facter --yaml" I see all the values as expected. See?

# facter --yaml | egrep '^ (fqdn|macaddress_eth0|lsbdistcodename|macaddress):'
lsbdistcodename: squeeze
macaddress_eth0: 00:12:a6:07:13:92
macaddress: "00:00:00:00:00:00"
fqdn: my.host.name.example.com


Is this a bug or a feature? Is there a workaround?

Thanks in advance,
Tom

P.S. macaddress and fqdn changed for obvious reasons.