[MERGE] get rid of os.spawnvp() usage for external diff

[Michael Ellerman]

On 6/9/06, James Henstridge <james at jamesh.id.au> wrote:
> This is a patch I did a while back to allow sending diff output to a
> file when using an external diff rather than just stdout.
>
> To do this, it changed external_diff() to use the subprocess module to
> invoke diff rather than os.spawnvp().  Since os.spawnvp() is not
> available on Windows (according to the Python documentation), this
> should also improve cross platform compatibility.
>
> The changes are available in following branch at revision 1698:
>     http://people.ubuntu.com/~jamesh/bzr/bzr.smallfixes
>
> The patch should fix bugs 4047 and 48914.

Looks good in general. +1 FWIW.

If I was picky I'd say it's a bit dicey to be moving all the localised
imports of sys up to the top level in this patch, that isn't really
logically part of this change.

I'm also not sure how well the tests will work on Windows, have you tried them?

cheers