Binary files cannot be diffed like text, but for some binary changes,
the diff algorithm does yield binary differences as text. With this
change, the diff builder and processor are taught to render a special
message for (non-image) binary diffs, and will ignore the text
representation of the delta.
Bug: Issue 4031
Change-Id: I2dcdbe9def006de827a37c35c42606bc1c9cf4fc