[BugReport] git tag -a / git show

["Romain Vimont (®om)" <rom@rom1v.com>]

$ git --version
git version 1.7.5.4

$ git log --pretty=online
0ef41513d0b6d0ad28f21d0ac1da7096ad1dc6ff This is the last commit
a4702c69c28484d357179166cf3b116764da20a4 This is a commit

Now, I edit some files (for example in a config file "mock_data=true"), 
then I want to tag without commiting this change.

$ git tag -a v0.1 -m 'My v0.1 with mock data'

$ git show v0.1
tag v0.1
Tagger: Me <me@me.me>
Date:   Fri Feb 24 11:23:38 2012 +0100

     My v0.1 with mock data

commit 0ef41513d0b6d0ad28f21d0ac1da7096ad1dc6ff
Author: Me <me@me.me>
Date:   Fri Feb 24 11:14:19 2012 +0100

     This is the last commit

diff --git a/myfile b/myfile
index 8430bf6..20feeb6 100644
...


And it shows the diff between a4702c69c28484d357179166cf3b116764da20a4 
and 0ef41513d0b6d0ad28f21d0ac1da7096ad1dc6ff (the two last commits).
Instead, it should show the diff between 
0ef41513d0b6d0ad28f21d0ac1da7096ad1dc6ff (the last commit) and v0.1 (the 
tag).

Best regards,
®om