After fresh Yosemite install SVN version is pretty old (I had 1.7.17), but don’t worry – upgrade process is simple but will take some time (15-25 mins depends on your CPU speed). This tutorial assumes you have XCode installed (but if you need SVN you probably have it):

1. Open terminal and paste

2. Create link to toolchain:

3. Download and unpack SVN 1.8.9:

4. Compile and install:

5. Check version:

You should see something like this:
svn, version 1.8.8 (r1568071)
(yes, I know I downloaded 1.8.9 but it shows 1.8.8 somehow…)