Asset too large when upload a zero byte file

[hidden-dimensions]

Error occurs when calling presign upload api with a zero bytes file:

curl -sS -X POST https://***.staging.skygearapp.com/_asset/presign_upload \
  -H "x-skygear-api-key: ***" \
  -H "Authorization: Bearer ***" \
  -H "Content-Type: application/json" \
  -d '{ "access": "private",
         "headers": {
            "cache-control": "max-age=3600",
            "content-type": "image/png",
            "content-length": "0"
          }
       }'

Response

{"error":{"name":"BadRequest","reason":"AssetTooLarge","message":"asset too large","code":400}}

• Skygear Server Date/Version: 0135aa2 as well as current staging.
• Application Platform:
• Is this a regression?
• Attached logs, screenshots

Expected Results

Should allow upload zero bytes file.

Actual Results

Steps to reproduce