Comment 17 for bug 1547466

I tried to backport http://git.savannah.gnu.org/cgit/gnulib.git/commit/?id=b7bc3c1a4 ; this by itself does not apply as this changes the files lib/hard-locale.[ch] (which aren't present at all in grep 2.24) and also has a lot of changes to files that aren't contained in grep. I got a backport now, but this still does not fix the bug.

I spent some half an hour making this work, but the longer I do this the less I have faith in the result. Therefore my recommendation is to drop this hackery-patchery and just upgrade xenial to grep 2.25 instead. The complete changelog is:

** Bug fixes

  In the C or POSIX locale, grep now treats all bytes as valid
  characters even if the C runtime library says otherwise. The
  revised behavior is more compatible with the original intent of
  POSIX, and the next release of POSIX will likely make this official.
  [bug introduced in grep-2.23]

  grep -Pz no longer mistakenly diagnoses patterns like [^a] that use
  negated character classes. [bug introduced in grep-2.24]

  grep -oz now uses null bytes, not newlines, to terminate output lines.
  [bug introduced in grep-2.5]

** Improvements

  grep now outputs details more consistently when reporting a write error.
  E.g., "grep: write error: No space left on device" rather than just
  "grep: write error".

(the first item is the fix for this bug). The other bug fixes are desirable for xenial as well, and the improvement seems harmless (and nice) enough to include it too.