Your bug report

#50115: date command arithmetic involving the epoch produces "invalid date"

which was filed against the coreutils package, has been closed.

The explanation is attached below, along with your original report.
If you require more details, please reply to 50115@debbugs.gnu.org.

-- 
50115: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=50115
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