Your bug report

#27838: grep error: "regexec.c:1375: pop_fail_stack: Assertion `num >= 0' failed."

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 27838@debbugs.gnu.org.

-- 
27838: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=27838
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