according to man sysctl.d, the file in /etc/ are reserved for the admin. Software should use /usr/lib/sysctl.d/ Each configuration file shall be named in the style of <program>.conf. Files in /etc/ override files with the same name in /usr/lib/ and /run/. Files in /run/ override files with the same name in /usr/lib/. Packages should install their configuration files in /usr/lib/.
*** This bug has been marked as a duplicate of bug 887017 ***