Before 'Moriturus te saluto', MIT (C) Scheme used to exit/terminate with the 'User halt code' message which is what Jim Miller chose when he implemented the original version of what at the time was called 'C Scheme'. The original implementation of MIT Scheme was on top of MacLisp running on a DEC PDP-10 computer , then re-written in a combination of Pascal and Motorola 68K assembly language to run on the HP 'Chipmunk' computers, and when there arose a need for a more 'portable' version, Jim started a version in C that could share binaries (Scode) with the 68K version. C Scheme was originally developed for DEC Vax minicomputers which were little endian, as opposed to the 68K which were little endian and the PDP-10 which was not even a byte-oriented computer. 
I had worked on both the MacLisp and 68K versions and at some point started working on C Scheme. I disliked 'User halt code' because the user (me) wasn't halting. :-) and picked the Latin version because it was fun.
I still believe that my change to 1st person singular is both correct and consistent with 'Morituri te salutamus' which is 1st person plural, as opposed to what would be a 3rd person singular version of 'Morituri te salutant' which is what it was eventually changed to claiming that my rendition was incorrect.
The sources claim that both 1st and 3rd person plural versions were used (or perhaps they can't decide), and hence the 1st person should be allowed, and I believe it is legal Latin although I only took Latin for one year in HS in 1977-1978.
Just to add a little to Arthur's story.
 This was an evolution of the very first Scheme interpreter that Gerry Sussman and Guy Steele implemented in the mid 1970s. Eventually it had a bit of PDP-10 assembly language as well as MacLisp didn't implement full tail recursion and various hacks were used to implement full tail recursion at some speed.
 Technically, Jim started developing C Scheme on a PDP 10 with an old C compiler, but he quickly moved to a Vax because the dialect of C on the PDP-10 was old and hence the code would not be very portable, and also because the PDP-10, sans extended addressing mode, could not address more than a 'Moby' (256 Kilowords of 36 bits each, a little over a megabyte) which was insufficient to keep up with the size of the system on the Chipmunks, especially with the heap split in two for the stop-and-copy garbage collector.