The helper for update expects and looks for options multi and upsert (also writeConcern and collation, and then as of 3.5.9 arrayFilters) and it silently ignores any and all other options.

This is bad because (a) misspelled options are silently ignored and the wrong thing happens (b) if we add new options in the future, they will also be silently ignored and not sent ahead to the server by older shell.