I just noticed that I forgot the header line of the diff. Sorry for that.
New double checked version attached.

The Changelog is still:
2009-12-15 Andreas Born  <futur.andy@googlemail.com>

      * kern/env.c (grub_env_export): Create nonexistent variables 
before exporting.

Andreas Born schrieb:
> Same here. Nothing changed as of r1917 and I didn't get any further 
> feedback either.
> I've attached a rediffed version, too.
>
> Andreas Born schrieb:
>> Here you go:
>> ChangeLog:
>> 2009-10-15  Andreas Born  <futur.andy@googlemail.com>
>>
>>       * kern/env.c (grub_env_export): Create nonexistent variables 
>> before exporting.
>>
>>
>> The mixed indentation (tabs and spaces) in kern/env.c was a bit 
>> confusing.
>>
>> Andreas
>>
>> Colin Watson schrieb:
>>> On Thu, Oct 15, 2009 at 08:40:37PM +0200, Andreas Born wrote:
>>>  
>>>> This patch changes grub_env_export to create variables with empty 
>>>> value,  if necessary.
>>>> This makes it possible to export variables before actually 
>>>> assigning  them any value and is the way bash behaves.
>>>>     
>>>
>>> This makes sense to me (although bash is "too big and too slow" and
>>> we'll never implement anything close to all of it, this is a pretty
>>> cheap way to reduce confusion due to differences), although probably 
>>> for
>>> post-1.97. A couple of nits:
>>>
>>>  
>>>>        * kern/env.c (grub_env_export): Create inexistent variables  
>>>> before exporting.
>>>>     
>>>
>>> "nonexistent"
>>>
>>>  
>>>> +  if (! var)
>>>> +  {
>>>> +    if (grub_env_set (name, "") != GRUB_ERR_NONE)
>>>> +        return grub_errno;
>>>> +    var = grub_env_find (name);
>>>> +  }        
>>>
>>> GNU brace style involves indenting the braces as well, thus:
>>>
>>>   if (! var)
>>>     {
>>>       if (grub_env_set (name, "") != GRUB_ERR_NONE)
>>>           return grub_errno;
>>>       var = grub_env_find (name);
>>>     }     
>>
>