Downloads never resume

[Will Holtz]

I've noticed that Managed Software Center is not resuming downloads for me. Here is the the test I'm running: request install from MSC, tail the logs to see when the download is partly done, turn off my wifi for a few minutes (long enough that MSC gives up on that download and perform postflight), turn my wifi back on,  in MSC Updates click 'Check Again', watch download start over from size 0 via logs and observing the Cache/foo.download file. I have verified that the etag information is being written to the Cache/foo.download file via xattr and does not change over time, however, the expected-length attribute is always "-1" while the file is downloading and then that attribute gets removed after I disconnect from the network. This is with Munki v3.1 and Simian for the server with the packages hosted at the default location (App Engine Blobstore).  

Has anyone else seen this? Does resuming of downloads generally work with Simian?

thanks,

-Will