Git can't merge two identical move file operation

Hello,

I have a git repo build using cvsimport. It has 'bad' directory
structure and I want to 'fix' it after each incremental update from
cvs. Here is the idea: I have 2 permanent branches master (to work
with) and cvs (to import from cvs) and one temporary branch to move
files across the project to make directory structure better. Movement
operation is always the same: move directories/files from one place to
another. But merging from temp branch to work branch fail with error
text :
CONFLICT (rename/delete): Rename a->b/a in HEAD and deleted in 791371

Here is the example script:

git version

git version 1.4.4

mkdir 1 && cd 1 && git init-db

defaulting to local storage area

echo 1 > a && git add a && git commit -a -m '1'

Committing initial tree 2ce1eef76631e82282e0f7f0cf9e6f3e9a4a0b1e

git checkout -b fix
mkdir b && git mv a b/ && git commit -a -m 'fix 1'
git checkout -b work master
git pull . fix

Updating 7be4ab0..d4909bb
Fast forward
 a => b/a |    0
 1 files changed, 0 insertions(+), 0 deletions(-)
 rename a => b/a (100%)

git checkout -f master
echo 2 >> a && git commit -a -m '2'
git checkout -b fix2 master
mkdir b && git mv a b/ && git commit -a -m 'fix 2'
git checkout -f work
git pull . fix2

Trying really trivial in-index merge...
fatal: Merge requires file-level merging
Nope.
Merging HEAD with 791371d91c34bc45b289319d96ebf35c8be385a0
Merging:
d4909bb fix 1
791371d fix 2
found 1 common ancestor(s):
7be4ab0 1
CONFLICT (rename/delete): Rename a->b/a in HEAD and deleted in
791371d91c34bc45b289319d96ebf35c8be385a0
Automatic merge failed; fix conflicts and then commit the result.

Bot fix and fix2 are temp branches and supposed to be deleted.

Why git can't merge such changes ? It should know that work holds
renamed version of file a from master and fix2 holds new renamed file
a from master too. Why it can't apply changes of a from master to work