Fix one more unicode issue in the svn client.
Fix one more unicode issue in the svn client.

This issue was reported to us via our commercial support tracker. The filename
in question is encoded as GBK, so running `svn status` on it and trying to
interpret the results as unicode is a bad idea.

Testing done:
Ran unit tests.

Reviewed at https://reviews.reviewboard.org/r/7320/

davidt/rbtools,datjwu/rbtools,haosdent/rbtools,reviewboard/rbtools,datjwu/rbtools,datjwu/rbtools,haosdent/rbtools,beol/rbtools,haosdent/rbtools,davidt/rbtools,beol/rbtools,beol/rbtools,reviewboard/rbtools,davidt/rbtools,reviewboard/rbtools