Allowed to 5 auth requests before fail (https://github.com/composer/composer/blob/6687743adbac1fe73ca81912a6ef29ceb6e5cc2f/src/Composer/Util/Svn.php#L115).
Updated tests for SVN driver.
Merge pull request #2008 from phansys/svn-auth

Allowed to 5 auth requests in svn before fail