Specify --patchlevel 0 to trychange.py

For some reason, trychange.py creates patches with level 0, even from a git
repo. We were assuming that the patch level was 1 from a git repo, so patches
were failing to apply.

BUG=skia:1669
R=rmistry@google.com

Review URL: https://codereview.chromium.org/61733011

git-svn-id: http://skia.googlecode.com/svn/trunk@12212 2bbb7eff-a529-9590-31e7-b0007b416f81
1 file changed