Crash when using git blame on untracked file

Hello,

I'm seeing the following crash with Git 2.9.3 on Debian sid (amd64):

    $ git init foo
    $ cd foo
    $ touch x
    $ git add x
    $ git commit -m test
    $ touch x.conf
    $ git blame x.conf
    segmentation fault

I've tested it on Debian stable's 2.1.4 which works fine:

    $ git blame x.conf
    fatal: no such path 'x.conf' in HEAD

It requires the blamed file to be present, but in some cases it works only if the file e.g. "x" is already tracked in Git and the other file is called "x.conf" (".conf"-suffix). But in an empty repo it seems to happen always.

Sadly Debian's git has no dbg-package, so the stacktrace is not very useful:

    #0  __strcmp_sse2_unaligned () at ../sysdeps/x86_64/multiarch/strcmp-sse2-unaligned.S:31
    #1  0x000000000041ad7a in ?? ()
    #2  0x0000000000406171 in ?? ()
    #3  0x0000000000405321 in ?? ()
    #4  0x00007ffff6f9f700 in __libc_start_main (main=0x4051c0, argc=0x3, argv=0x7fffffffe1a8, init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x7fffffffe198)
        at ../csu/libc-start.c:291
    #5  0x00000000004057d9 in ?? ()

Regards Simon