XLSX roundtrip problem (added underscores)

[memowe]

Failures:

  test/LiBro/UtilSpec.hs:104:29: 
  1) Helper stuff, XLSX data conversion, Load . store = id, With arbitrary data, Correct output data
       Falsifiable (after 3 tests and 3 shrinks):
         [ED {foo = -1, bar = "r\ACK@"}]
       expected: Right [ED {
                   foo = -1,
                   bar = "r\ACK@"
                 }]
        but got: Right [ED {
                   foo = -1,
                   bar = "r_x0006_@"
                 }]

\ACK and \x0006 are the same character, but libreoffice adds underscores.

Does not seem to happen on my fedora machine.

LibreOffice version: 6.4.7.2 40(Build:2)