(Forked from https://bitbucket.org/hamano/nginx-mod-am)
The fix introduced in this fork (CDSSO post handling problem -> https://github.com/tegioz/nginx-mod-am/commit/3b1955534d2396a7ba8ae301dc8bb77782f017c0) has already been merged into the main module repository (as well as in the OpenAM incubator branch), so you should use it instead of this one.
https://bitbucket.org/hamano/nginx-mod-am
https://bugster.forgerock.org/jira/browse/OPENAM-1182
https://github.com/tegioz/nginx_openam_build