The UTC has just issued a correction for UAX-14 Line Breaking, revising rule LB8 to be
ZW SP* ÷
This needs to be implemented in ICU line break.
It appears that this may be somewhat more difficult than I had originally anticipated.
Ticket 9030, for break engine enhancements, must be done before this change can be implemented.
Rescheduling this ticket for 61. With the removal of the reverse rules in ICU 60, implementation should now be possible.