Error: Package tuple  could not be found in packagesack.if you get this message  if you make changes to
from the default in your /etc/yum.conf or any of your *.repo files in /etc/yum.repos.d/,
for this only workaround is to clean the yum repository.

solution for this  yum repository that I found by disabling all the yum repositories  and re-enabling them 1 by one.this worked for me,hope it will work for all.

Please commecnt on this post so that  if you know any alternative workaround for this.