You may see these messages on some servers, reported LANG will likely be different (according to your environment)
svn: warning: cannot set LC_CTYPE locale svn: warning: environment variable LANG is en_GB.UTF-8 svn: warning: please check that your locale name is correct
This is caused by not having the proper locales generated on your system.
Update the file
/etc/locale.gen to include the locales you want to support.
en_GB.UTF-8 UTF-8 en_US.UTF-8 UTF-8
Next run the program called
locale-gen to rebuild the necessary files.
The envrionment may need to be updated as well, that is
/etc/profile or similar.
On Gentoo check
env-update and then source