Known mock/yum problem?

[Paul Howarth]

Came across an oddity today and I'm not sure if it's mock or yum that's 
the problem.

I'm running with these updates from updates-testing (on an FC7 host):
mock-0.7.2-1.fc7
yum-3.2.1-1.fc7

My rawhide mock config points to a single baseurl for the fedora repo, 
and goes through a local squid proxy. I'm also using autocache.

 From time to time packages cannot be retrieved over the network, 
perhaps due to the mirror being in mid-sync, or maybe transient network 
issues.

Sometimes this results in one or more (but not all) packages not being 
available to populate a buildroot when running mock. When this happens, 
mock is not terminating the build during the setup phase, and allows it 
to continue to the build phase. I noticed this problem because it often 
results in a failed build due to to some important missing buildreq.

More worrying though is the possibility that a missing buildreq package 
may be needed only to enhance the functionality of the package being 
built. In such cases the overall build may succeed but produce a package 
with reduced functionality, and be different from the same package 
rebuilt by someone else on their own system.

So is this yum not returning a proper exit code, or mock ignoring it? 
I'm not sure.

Is this a known issue? I couldn't see anything that looked like this in 
bugzilla.

Paul.