http://cdimage.kali.org/kali-images/kali-weekly/SHA256SUMS redirects me to
http://mirrors.dotsrc.org/kali-images/kali-weekly/SHA256SUMS

Request URL:http://cdimage.kali.org/kali-images/kali-weekly/SHA256SUMS
Request Method:GET
Status Code:302 Found
Remote Address:192.99.200.113:80
Referrer Policy:no-referrer-when-downgrade

Response Headers:
Connection:Keep-Alive
Content-Length:326
Content-Type:text/html; charset=iso-8859-1
Date:Sun, 30 Jul 2017 12:15:05 GMT
Keep-Alive:timeout=5, max=100
Link:<http://ftp.belnet.be/kali/kali-images/kali-weekly/SHA256SUMS>; rel=duplicate; pri=4; geo=be
Link:<http://ftp2.nluug.nl/os/Linux/distr/kali-images/kali-weekly/SHA256SUMS>; rel=duplicate; pri=5; geo=nl
Link:<http://cdimage.kali.org/kali-images/kali-weekly/SHA256SUMS.meta4>; rel=describedby; type="application/metalink4+xml"
Link:<http://mirrors.dotsrc.org/kali-images/kali-weekly/SHA256SUMS>; rel=duplicate; pri=1; geo=dk
Link:<http://archive-3.kali.org/kali-images/kali-weekly/SHA256SUMS>; rel=duplicate; pri=2; geo=de
Link:<http://ftp.halifax.rwth-aachen.de/kali-images/kali-weekly/SHA256SUMS>; rel=duplicate; pri=3; geo=de
Location:http://mirrors.dotsrc.org/kali-images/kali-weekly/SHA256SUMS
Server:Apache/2.4.10 (Debian)
X-MirrorBrain-Mirror:mirrors.dotsrc.org
X-MirrorBrain-Realm:region

SHA1SUMS do the same

'http://mirrors.dotsrc.org/kali-images/kali-weekly/SHA256SUMS' Contains only checksum for previous version (W30), not for W31.