bug with sort (coreutils) 4.5.3 ?

[Eric Hoth]

I believe there's a bug in the sort command in version 4.5.3.

I'm trying to sort a list by month:

echo "jan
feb
mar
apr
may
jun" | sort -M

and it returns the list in alphabetical order, not by month. I've tried
both the -M and the --month-sort options. This is /bin/sort on a new
RedHat 9.0 install. The --version command says I'm running sort
(coreutils) 4.5.3.

I have an older linux box with version sort (textutils) 2.0.21 which
works and sorts months properly.

If I'm way off on this and it's not a bug but just something dumb I'm
doing, please let me know.

Eric