(wrong-type-argument stringp nil) in latest git head about elpy

[lvh]

Using git-bisect, I was able to find the commit that causes this error on startup:

a353ff678475d0c3c0e67c19ecc94c8fd864e158 is the first bad commit
commit a353ff678475d0c3c0e67c19ecc94c8fd864e158
Author: Jorgen Schaefer <[email protected]>
Date:   Sun Feb 3 13:29:17 2013 +0100

    New build environment: Build a .tar for Marmalade/Elpa.

    The new build script `build.sh` will create the appropriate directory
    and tar file, including the elpy-pkg.el from the new file
    elpy-pkg.el.in with all the dependencies. Those have been remove from
    elpy.el.

    python-check.sh is now included in the tarfile, and elpy.el will
    initialize python-check-command with it if it can be found.

    Fixes #13

:000000 100755 0000000000000000000000000000000000000000 a46b22975019c16b7e74ea0c074701af052dcf22 A  build.sh
:000000 100644 0000000000000000000000000000000000000000 1b7e196e43ff3a3474dd74e997b15a1761981b53 A  elpy-pkg.el.in
:100644 100644 affc2992deede845b8fe069efde92eb7eb4df95b 7fdba53af4003c3928788c502a09e94904b619d7 M  elpy.el

Hope that helps :)