Weird value on %<fsiz> field in log files

We've configured ATS as a reverse proxy, and We've been noticed a really weird traffic value in our monitoring system. After spend some time digging through log files, I could notice that, in some cases the field %<fsiz> brings a huge value (20 characters) instead of the file size.

I found this closed issue regarding the <fsiz> implementation, and I think there might be a issue when there is no Content-Length from the origin server.

https://issues.apache.org/jira/browse/TS-2212

Log format:
##########################
<LogFormat>
<Name = "myformat"/>
<Format = "%<ttmsf> %<

{Host}

cqh> %<chi> [%<cqtn>] %<cqhm> %<cquup> %<cqhv> %<pssc> %<cqhm> %<fsiz> %<cquup> %<

{User-Agent}

cqh> %<

{Referer}

cqh> %<crc>"/>
</LogFormat>
##########################

Log result:

##########################
0.181 myhostname.com 123.123.123.123 [17/Jul/2014:15:50:33 -0000] GET /foo/bar/file.jpg HTTP/1.1 200 GET 3904675161847313968 /foo/bar/file.jpg Mozilla/5.0 (Windows NT 6.2; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/35.0.1916.153 Safari/537.36 http://myreferer.com TCP_MISS

###########################

In that case, the <fsiz> field has the value "3904675161847313968" instead the value of a few bytes.
I believe when there is no way to get the real content-length, we should return 0 in order to avoid misinterpretation.

Thanks in advance,
Daniel