Nginx generating different md5 sums for same key causing cache to become corrupt

[pirish]

Hello,
  Currently we use nginx 1.8.1 on redhat 7.  We have reverse proxy caching
enabled but are experiencing unexpected behaviour.  Our caching key is
$scheme$request_method$host$request_uri$.  On the first visit to a page, a
cache file with the correct md5 sum of the key is created.  If you visit the
same url from the same browser, but a different tab, a new cache file is
created with different md5 sum, but same content.  The next time you visit
the url from that browser, it will be random which page is selected from the
cache.  Now if you visit from a second browser a 3rd cache file will be
created.  Reloading from any browser or tab will randomly pick one of the
created files.  Are there other factors in creating the md5 other than the
cache key ?

Posted at Nginx Forum: https://forum.nginx.org/read.php?2,265703,265703#msg-265703