bug#28847: Maybe a bug in "sort (GNU coreutils) 8.4" report

[kakaxixi777]

   Dear coreutils :
   I am a Research and Development Engineer in IT. I met a situation when
   I use “sort” command in Linux shell which could be a bug for the "sort"
   command. So I hope you read this email, thank you !
   The whole command I used was ：
   sort test.txt
   And the result was :
   20171012|3|2059517|-|8|-|20-24|2|-|2.0|2.0
   20171012|3|2059517|-|82|-|25-29|2|-|13.0|12.0
   20171012|3|2059517|-|8|-|-2|-2|-|71.0|64.0
   20171012|3|2059517|-|82|-|30-34|0|-|2.0|1.0
   The content in test.txt was:
   20171012|3|2059517|-|8|-|20-24|2|-|2.0|2.0
   20171012|3|2059517|-|82|-|25-29|2|-|13.0|12.0
   20171012|3|2059517|-|8|-|-2|-2|-|71.0|64.0
   20171012|3|2059517|-|82|-|30-34|0|-|2.0|1.0
   Which means the “sort” command didn't work, because I think the correct
   result should be :
   20171012|3|2059517|-|8|-|20-24|2|-|2.0|2.0
   20171012|3|2059517|-|8|-|20-24|2|-|2.0|2.0
   20171012|3|2059517|-|82|-|25-29|2|-|13.0|12.0
   20171012|3|2059517|-|82|-|25-29|2|-|13.0|12.0
   The version of "sort" command I use is : sort --version
   "sort (GNU coreutils) 8.4
   Copyright (C) 2010 Free Software Foundation, Inc.
   License GPLv3+: GNU GPL version 3 or later
   <http://gnu.org/licenses/gpl.html>.
   This is free software: you are free to change and redistribute it.
   There is NO WARRANTY, to the extent permitted by law.
   Written by Mike Haertel and Paul Eggert."
   I am not sure if it is a bug in "sort" command in Linux Shell or maybe
   it's only my problems in using it.
   So I am look forward to receive your reply as soon as possible.
   Thank you very much!
Sincerely yours,
Frank