Segmentation fault git pull

[Len Brown <lenb@kernel.org>]

$ git --version
git version 1.5.6.3.439.g1e10

...while doing a pull on my vanilla linus' linux tracking tree,
which I have not touched in about a week.

$ good.morning
...
+ git checkout master
Already on "master"
+ git pull
remote: Counting objects: 31759, done.
remote: Compressing objects: 100% (5397/5397), done.
remote: Total 28193 (delta 23770), reused 27116 (delta 22765)
Receiving objects: 100% (28193/28193), 6.76 MiB | 526 KiB/s, done.
Resolving deltas: 100% (23770/23770), completed with 3141 local objects.
From git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6
   f57e916..33af79d  master     -> origin/master
From git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6
 * [new tag]         v2.6.26    -> v2.6.26
Updating f57e916..33af79d
/lab/bin/good.morning: line 8:  5610 Segmentation fault      git pull
...
$ git pull
Updating f57e916..33af79d
fatal: unable to create '.git/index.lock': File exists
[lenb@d975xbx2 linus (master)]$ rm .git/index.lock

git status
shows no local changes, just a few untracked files i have left around.

clues?

thanks,
-Len

ps.
$ cat /lab/bin/good.morning 
#!/bin/bash -x
cd ~/src/git
git checkout master
git pull
make -j4 install
cd ~/src/linus
git checkout master
git pull
...