The only things we mount from mock are: /proc, /sys, /dev/pts
I have seen that in mountCmds and I'd tell you're right. Hence I guess
they get mounted by some other means, but i don't know why and how.
What package(s) are you building?
It happens to me all the time with all kind of packages. Most of them
are just jars with some config files that are actually built by a
separate machine and are just rpm-packaged via mock, others are python
projects which are treated in a similar fashion; we never build anything
too strictly system or kernel related. The chroot is a centos5-64 bit one.
I'll try reproducing the issue on a freshly-installed system with stock
configuration, in order to find out what triggers it.
contact me at public(a)[mysurname].eu