[merge] Enhancement to also use the external diff tool for new and deleted files.

[David Ingamells]

Aaron Bentley wrote:
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> David Ingamells wrote:
>   
>> Extend bzr to also pass added and deleted files to the external diff
>> tool when "bzr diff --using" is called.
>>     
>
> Thanks for your submission.
>
> diff --using shouldn't interfere with creating correct diffs, but this
> change does.
>
> A diff that deletes a file superficially resembles a diff that changes
> the file's size to 0.  But there are differeces.  A deletion diff will
> show /dev/null as the path to the 0-size file, and it will show the UNIX
> epoch as the modified time of the 0-size file.  The inverse is true for
> patches that create files.  These hints are used by patch to decide
> whether to delete a file or change its contents.
>
> As it stands, this change will cause incorrect patches to be generated
> when doing diff --using diff.
>   

Please forgive my ignorance. :-[

Is the external diff tool used to create patches? I was under the 
impression that "bzr send" did that (or "bzr diff -p1" and that "bzr 
diff --using" was for producing human friendly display for reviews.

If /dev/null is the 0-sized file, then how does one change the 
modification time of it? What is the "inverse" of this?

> bb:resubmit
>
>   
>> Feel free to be extra critical  ;-)   as this is my first submission to
>> bzr *and* my first work with python.
>>     
>
> Your mother was a hamster, and your father smelled of elderberries. ;-)
>
>   
I wasn't meaning *that* kind of Python. I'm old enough to have seen 
*that* Python first-time around :-(