bug#24072: sed bug search or replace newline chars

[Bee]

lubuntu 16.04
sed --version
sed (GNU sed) 4.2.2

I have recurring files exported from a database with stray newline chars.  I 
would like to remove them with sed but nothing is changed.

It works to use tr:
cat xxx.txt | tr '\n' '\t' > yyy.txt

These hex and control codes work:
sed -e 'y/\x0d/\x09/' xxx.txt > yyy.txt
sed -e 'y/\r/\x09/' xxx.txt > yyy.txt
sed -e 'y/\r/\t/' xxx.txt > yyy.txt

But these do nothing:
sed -e 'y/\x0a/\x09/' xxx.txt > yyy.txt
sed -e 'y/\n/\x09/' xxx.txt > yyy.txt

Is this a bug?

Bill Muench
Santa Cruz, California