bug#32450: uniq -f: unexpected behaviour

[helo]

> I'm not observing this problem in coreutils 8.29, the current version. [...]

It took me a while to reproduce the problem. It seems, I startet with 
$ echo "
1 1 1
1 2 3
1 1 4
2 4 4 
" | uniq -c f2
trying to sort some values. Then I went "up" in the history and deleted the 
unneeded newlines (also changing the sort-field value, so suddenly the output 
was the one I submited as bug. Then I tried to sort some letters, and the bug 
did not appear. So I thougt, it might have to do with letters and numbers - and 
of cause with the field-value in sort. 

Actually this was / is the problem:

## tl;dr ##
$ echo -e "a""\n""a" | uniq      # I use doublequotes to distinguish the 
characters
a
$ echo -e "a""\n""a"" " | uniq   # I think this one happened to me; could not 
see it in i/o
$ echo -e "a""\n""\r""a" | uniq  
a
a

# note: the control character could be before / after one of the values 
#       it works same way with "\a" and "\b"

So it is not an unexpected behaviour of uniq -f, but of uniq / sort -u.