gitk Branch: field problem with 1.6.1

Greetings,

If I create a test repository as follows...

mkdir gitktest
cd gitktest
git init
echo foo > foo
git add foo
git commit -m "foo"
echo bar >> foo
git add foo
git commit -m "bar"
git checkout -b branch HEAD~1
echo baz > baz
git add baz
git commit -m "baz"
echo baz >> baz
git add baz
git commit -m "more baz"
git checkout -b debug2
echo baz >> baz
git add baz
git commit -m "even more baz"

...and with gitk --all look at the "more baz" commit, it says
"Branch: debug2" as shown here
<http://www.iki.fi/azure/tmp/gitk-test1.png>.  My understanding is
that it should show "Branches: branch, debug2" but I might be wrong
of course.

I have another test repository (I can make a creation recipe or
make the repository available for download if needed) where, in
addition to the problem above, gitk shows empty "Branch:" field for
the master branch's tip commit.

Both tests made with 1.6.1 on Linux.

-- 
Hannu