I like the idea of the new ':/<oneline prefix>' notation, and gave it

I like the idea of the new ':/<oneline prefix>' notation, and gave it
a try, but all I could get was a segfault.  It was dereferencing a NULL
commit list.  Fix below.  With it, this example now works:

    $ mkdir .j; cd .j; touch f
    $ git-init; git-add f; git-commit -mc f; echo x >f; git-commit -md f
    $ git-diff -p :/c :/d
    diff --git a/f b/f
    index e69de29..587be6b 100644
    --- a/f
    +++ b/f
    @@ -0,0 +1 @@
    +x

Signed-off-by: Jim Meyering <jim@meyering.net>
Signed-off-by: Junio C Hamano <junkio@cox.net>