To properly install subversion 1.9 from Wandisco, you should do the following:

Create a new repo file /etc/yum.repos.d/wandisco-svn.repo with following content:

[WandiscoSVN]
name=Wandisco SVN Repo
baseurl=http://opensource.wandisco.com/centos/$releasever/svn-1.9/RPMS/$basearch/
enabled=1
gpgcheck=0

Then install svn with following command:

yum --disablerepo="*" --enablerepo="WandiscoSVN" install subversion