Possible bug in `sort'

I noticed that sort sometimes sorts '-' before '1' and sometimes
after. Here is an example, together with relevant version numbers.

TIA, David.


Script started on Sun Jun 13 15:20:31 2004
tmp-> cat sort.ex1  
1
-1
tmp-> cat sort.ex2
1,
-1
tmp-> sort sort.ex1
1
-1
tmp-> sort sort.ex2
-1
1,
tmp-> sort --version
sort (GNU textutils) 2.0e
Written by Mike Haertel.

Copyright (C) 1999 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
tmp-> uname -a
Linux flash 2.4.5 #1 SMP Wed Jul 18 16:34:35 IDT 2001 i686 unknown
tmp-> rpm -q -a | grep redhat-release
redhat-release-7.0-1
tmp-> exit
Script done on Sun Jun 13 15:21:44 2004