Recently we started having problems with Subversion failing to resolve the hostname of a remote repository. Some customers on chrooted shells experienced this problem after we upgraded a series of Linux libraries in the Plesk servers.
After much investigation (there is very little information about this on the web) we found that the solution is quite simple. Copying the /etc/resolv.conf file to the etc directory of the chroot account solves the problem.
Hopefully this post saves several hours of someone else having a similar problem.