Skip running svn tests when svn isn't installed
Skip running svn tests when svn isn't installed

Signed-off-by: Harsh Vardhan <9b4b79688aa14b36c37ee9498099be18ac2c608a@gmail.com>

pfmoore/pip,xavfernandez/pip,pradyunsg/pip,pypa/pip,xavfernandez/pip,pfmoore/pip,pypa/pip,xavfernandez/pip,sbidoul/pip,pradyunsg/pip,sbidoul/pip