There's a problem in HFS 1.6 rc8 where HFS would ignore the resume request and sends from the beginning of the file.
Here's an example:
I set up a text file called "Testing.txt" in HFS (8 bytes) with the contents:
00001111
and with this bug:
*** GET REQUEST ***
GET /Testing.txt HTTP/1.1
Host: 127.0.0.1
Accept: */*
Range: bytes=4-
Pragma: no-cache
Cache-Control: no-cache
Connection: close
*******************
*** RESPONSE ***
HTTP/1.1 206 Partial Content
Content-type: text/plain
Content-range: bytes 4-7/8
Content-length: 4
Server: HFS 1.6 rc8
Content-Disposition: attachment; filename="Testing.txt"
0000
****************
As you see from the example above, HFS doesn't send the 1's but instead send from the beginning of the file, resulting a corrupted file on resume.
If the download isn't interrupted in between, the download would work just fine.