Fetcher has unclear error message on HEAD fetch stage or cache sizing

$ curl -L -v -O -s http://HOSTNAME_REDACTED/PATH_REDACTED.tar.gz
*   Trying 172.17.4.10...
* Connected to HOSTNAME_REDACTED (172.17.4.10) port 80 (#0)
> GET /PATH_REDACTED.tar.gz HTTP/1.1
> Host: HOSTNAME_REDACTED
> User-Agent: curl/7.43.0
> Accept: */*
>
< HTTP/1.1 302 FOUND
< Server: nginx/1.4.6 (Ubuntu)
< Date: Mon, 05 Jun 2017 17:58:04 GMT
< Content-Type: text/html; charset=utf-8
< Content-Length: 1947
< Connection: keep-alive
< Location: https://BUCKET_REDACTED.s3.amazonaws.com:443/PATH_REDACTED?Signature=REDACTED%3D&Expires=1496689084&AWSAccessKeyId=KEY_REDACTED&x-amz-security-token=TOKEN_REDACTED%3D
<
* Ignoring the response-body
{ [309 bytes data]
* Connection #0 to host HOSTNAME_REDACTED left intact
* Issue another request to this URL: 'https://BUCKET_REDACTED.s3.amazonaws.com:443/PATH_REDACTED.tar.gz?Signature=SIGNATURE_REDACTED%3D&Expires=1496689084&AWSAccessKeyId=KEY_REDACTED&x-amz-security-token=TOKEN_REDACTED%3D'
*   Trying 54.231.40.75...
* Connected to BUCKET_REDACTED.s3.amazonaws.com (54.231.40.75) port 443 (#1)
* TLS 1.2 connection using TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256
* Server certificate: *.s3.amazonaws.com
* Server certificate: DigiCert Baltimore CA-2 G2
* Server certificate: Baltimore CyberTrust Root
> GET /PATH_REDACTED.tar.gz?Signature=REDACTED&Expires=1496689084&AWSAccessKeyId=KEY_REDACTED&x-amz-security-token=TOKEN_REDACTED%3D HTTP/1.1
> Host: BUCKET_REDACTED.s3.amazonaws.com
> User-Agent: curl/7.43.0
> Accept: */*
>
< HTTP/1.1 200 OK
< x-amz-id-2: ID_REDACTED=
< x-amz-request-id: REQUEST_ID_REDACTED
< Date: Mon, 05 Jun 2017 17:58:07 GMT
< Last-Modified: Thu, 01 Jun 2017 03:04:49 GMT
< ETag: "ETAG_REDACTED"
< Accept-Ranges: bytes
< Content-Type: application/x-tar
< Content-Length: 208245664
< Server: AmazonS3
<
{ [16360 bytes data]

fetcher.cpp:479] Reverting to fetching directly into the sandbox for 'http://HOST_REDACTED/PATH_REDACTED.tar.gz', due to failure to fetch through the cache, with error: Could not determine size of cache file for 'USER_REDACTED@http://HOST_REDACTED/PATH_REDACTED.tar.gz' with error: No URL content-length available