+ * incompatible change: an interruption (be it a function passed to
+ INTERRUPT-THREAD or a timer function) runs in an environment where
+ interrupts can be enabled. The interruption can use
+ WITH-INTERRUPTS or WITHOUT-INTERRUPTS as it sees fit. Use
+ WITHOUT-INTERRUPTS to avoid nesting of interruptions and
+ potentially running out of stack. Keep in mind that in the absence
+ of WITHOUT-INTERRUPTS some potentially blocking operation such as
+ acquiring a lock can enable interrupts.
+ * incompatible change: GC-OFF and GC-ON are removed, as they were
+ always unsafe. Use WITHOUT-GCING instead.