Make svndiff.py work on Windows and with svn 1.7.

R=epoger@google.com

Review URL: https://codereview.chromium.org/25447003

git-svn-id: http://skia.googlecode.com/svn/trunk@11642 2bbb7eff-a529-9590-31e7-b0007b416f81
2 files changed