Weird checksum changes

[MK-MacPorts at techno.ms]

On Sep 18, 2013, at 12:31 AM, Ryan Schmidt wrote:

> On Sep 17, 2013, at 16:46, MK-MacPorts at techno.ms wrote:
> 
>> I was puzzled by the fact that just a few minutes ago I had a weird case of a changing checksum for litecoin's tarball.
>> When I first checked in the new version on my local machine I had valid three checksums.
>> Then all three of MacPorts' buildbots
>> 	http://build.macports.org/builders/buildports-mtln-x86_64/builds/8209
>> 	http://build.macports.org/builders/buildports-lion-x86_64/builds/14371
>> 	http://build.macports.org/builders/buildports-snowleopard-x86_64/builds/20719
>> complained about a wrong checksum.
> 
> The buildbots either already had the old distfile or downloaded them from distfiles.macports.org (since it will have the lowest ping time). Hence the need for following the stealth-update recipe and changing the dist_subdir.

Still, I wonder why the checksums were different here on my local machine and on the buildbots in the first place.

I thought that github (isn't | wouldn't be) changing the contents of their tarballs all the time!?