make tgz downloads produce the same file every time


Thanks for the tgz downloads, it makes it really easy to get source tarballs 
for tagged releases for packaging things in Debian. But there is a problem: 
each time someone downloads a file using a given link, they each get a 
different file.  At the very least, the tarball should use timestamps from the 
git commit instead of the current time.

What steps will reproduce the problem?
1. wget 
https://android.googlesource.com/platform/build/+archive/fc5aee3a58d6077725795fe
f3458dd787a8a1042.tar.gz
2. wget 
https://android.googlesource.com/platform/build/+archive/fc5aee3a58d6077725795fe
f3458dd787a8a1042.tar.gz
3. diff fc5aee3a58d6077725795fef3458dd787a8a1042.tar.gz 
fc5aee3a58d6077725795fef3458dd787a8a1042.tar.gz.1
4. ls -l fc5aee3a58d6077725795fef3458dd787a8a1042.tar.gz 
fc5aee3a58d6077725795fef3458dd787a8a1042.tar.gz.1

What is the expected output? What do you see instead?

The tarballs should be exactly the same since they supposedly including the 
exact same files from the same commit.  But there are differences, the 
timestamps in the tar files are the time downloaded, when really, it should 
just reuse the timestamp from the git commit being downloaded.  Also, the size 
of the files differ, but that might just be because of varying compression of 
the timestamps (I got 6499655 and 6499618 for the above file).

Original issue reported on code.google.com by h...@guardianproject.info on 19 Feb 2016 at 8:42

a780201 / gitiles

make tgz downloads produce the same file every time #98