How to verify that lines were only moved, not edited?

I thought there was a way to use git-blame to find out whether a change
only shuffled lines, but otherwise did not modify them. I tried "git blame
-M -- the/file", but it does not work as expected, neither with a toy file
nor with a 5000+ lines file (with 55 lines moved).

git init
echo A > foo
echo B >> foo
git add foo
git commit -m initial
echo B > foo
echo A >> foo
git commit -a -m swapped

The results are:
$ git blame -M -s -- foo
^e3abca2 1) B
6189cb46 2) A

I would have expected:
^e3abca2 1) B
^e3abca2 2) A

Oh, look! This produces the expected result:
$ git blame -M1 -s -- foo

while this produces the same as with just -M:
$ git blame -M2 -s -- foo

But neither helps with my 5000+ lines file. Does it mean that the lines
were changed? But I'm sure they were just moved! Please help!

-- Hannes