Use sudo for wiping old image content; it occasionally can be root owned.

BUG=chromium-os:32219
TEST=manual; force src/build/images/some/path to root, ensure it works.

Change-Id: Ic73adeb9fadc1ef982bd08ffc3914c469e48e42c
Reviewed-on: https://gerrit.chromium.org/gerrit/26527
Tested-by: Brian Harring <ferringb@chromium.org>
Reviewed-by: David James <davidjames@chromium.org>
1 file changed