+ * bug fix: functions with non-required arguments used to end up with
+ (SB-C::&OPTIONAL-DISPATCH ...) as their name.
+ * bug fix: redefining a function with non-required arguments didn't
+ update the system's knowledge about its call signature properly.
+ * bug fix: fixed #431; incompatible alien record type redefinitions
+ are detected and handled. (reported by Neil Haven)