downloading a zipped folder yields different md5 hash every time

[drammock]

(I can't tell if this issue belongs here, in waterbutler, or somewhere else, so forgive me / feel free to migrate this issue if it's in the wrong place)

When downloading a zipped folder through the OSF API, like this:
https://files.de-1.osf.io/v1/resources/52rea/providers/osfstorage/5cf7eedee650a2001ad560f2/?zip=

The generated zip file will have a different md5 hash every time. This is probably because the server zip utility is including extra information about the zipped files (most probably a timestamp for last accessed or something; cf. this stackoverflow answer). If possible, can you disable the inclusion of extra information so that generated zip files will have the same hash each time?

ps: I'm aware that I can get the hashes of individual files from the JSON API, but it is much easier to test the hash of the downloaded archive rather than unpacking first and then testing each file separately.