Patch by Andi Albrecht to fix issue 18: diff of empty added file causes 500 error.
Patch by Andi Albrecht to fix issue 18: diff of empty added file causes
500 error.

riannucci/rietveldv2,nicko96/Chrome-Infra,nicko96/Chrome-Infra,riannucci/rietveldv2,nicko96/Chrome-Infra,nicko96/Chrome-Infra,nicko96/Chrome-Infra