@droark mentioned the expat download was failing when trying to gitian build 0.16. I tried locally and also saw issues:
0make download
1Checksum missing or mismatched for expat source. Forcing re-download.
2Fetching expat-2.2.1.tar.bz2 from https://downloads.sourceforge.net/project/expat/expat/2.2.1
3 % Total % Received % Xferd Average Speed Time Time Time Current
4 Dload Upload Total Spent Left Speed
5 0 0 0 0 0 0 0 0 --:--:-- 0:00:01 --:--:-- 0
6100 652 100 652 0 0 361 0 0:00:01 0:00:01 --:--:-- 0
7/Users/xxx/Github/bitcoin/depends/work/download/expat-2.2.1/expat-2.2.1.tar.bz2.temp: FAILED
8shasum: WARNING: 1 computed checksum did NOT match
9Fetching expat-2.2.1.tar.bz2 from https://bitcoincore.org/depends-sources
10 % Total % Received % Xferd Average Speed Time Time Time Current
11 Dload Upload Total Spent Left Speed
12 0 0 0 0 0 0 0 0 --:--:-- 0:00:01 --:--:-- 0
13curl: (22) The requested URL returned error: 404 Not Found
14make[1]: *** [/Users/xxx/Github/bitcoin/depends/sources/download-stamps/.stamp_fetched-expat-expat-2.2.1.tar.bz2.hash] Error 22
15make: *** [download-linux] Error 2
This switches to downloading from GitHub, as we are doing in master.