Differences between koji and mock rawhide environments?

[Tom Lane]

postgresql is currently failing to rebuild in rawhide:
http://koji.fedoraproject.org/koji/taskinfo?taskID=3499379
This seems quite repeatable, in koji, but the package builds fine on my
workstation under mock's fedora-rawhide-x86_64 and fedora-rawhide-i386
environments.  Shouldn't this have exactly the same results?  Can anyone
suggest how I might reproduce the failure someplace where I can debug it?

			regards, tom lane