That's not an aufs bug.
Unpacking httpd is failing because one of its files (/usr/sbin/suexec) has a filesystem capability set (cap_set_file). The Linux kernel doesn't allow unprivileged users (and therefore unprivileged containers) to set such capabilities on files.
@hallyn has been working on a kernel fix to this problem for quite a while now. Once that fix is merged in the upstream kernel, installing such packages will then work fine.
Until then, you have only a few options:
- Use a privileged container rather than an unprivileged one
- Stay away from any affected packages
- Use another Linux distribution for your container