If the installer did that, it's very likely that your rc.subr was modified (not corresponding to the genuine one of 14.3-RELEASE).it got to merging rc.subr,
I agree that the questions you get during the merge process are obscure, except when you know exactly why you modified the file.
In fact, unless there is no other solution and it's mandatory for your system (I believe there is always another solution), you should never touch a file in /etc except rc.conf and sysctl.conf (there is maybe one or two others).
Before to report a bug, try to understand why you got this problem. It's possible there is a bug somewhere in the merge process. But, this affects only you, apparently. If you don't give the means to reproduce this problem, it got never fixed.