Feedback from upstream: Now, the default value of fallback-input-method is "lsymbol, unicode". So all input methods (not only rfc1345) are given mapping for "/" (from lsymbol.mim) and "C-u" (from unicode) unless they themselves define mappings for those characters.
If a user does not like this feature, one can customize the value of fallback-input-method defined in global input method to an empty string by using the tool "m17n-im-config", or by having this code in ~/.m17n.d/config.mic. ((input-method t nil global) (variable (fallback-input-method nil "")))
