I plan to push these parse-datetime.y changes to gnulib:
http://thread.gmane.org/gmane.comp.lib.gnulib.bugs/27929/focus=27953
(doc changes can wait a few days, if needed)
and then the corresponding change to make coreutils use it,
add a test and to note the improvement in NEWS:
http://thread.gmane.org/gmane.comp.gnu.coreutils.general/1518
That should happen tomorrow.
Then I'll make a snapshot, which we'll let settle for at least a
couple of days before releasing coreutils-8.13 some time next week.