Re: patch subtraction bug

[Tim Waugh <twaugh@redhat.com>]

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On Mon, 2006-10-23 at 17:26 -0500, Eli Carter wrote:
> I tried abusing patchutils in a new way today, and it didn't do what I
> wanted.
> 
> First, pull one change out of a larger patch:
> filterdiff -p1 -i some/file.py --hunks=5 < diff > one-change.patch
> Now, I want to remove that change from the larger patch, so I combine the
> larger patch with a reversed version of the the one-change.patch:
> interdiff one-change.patch /dev/null | combinediff diff /dev/stdin >
> rest.patch
> 
> What I got was a patch with the hunk from one-change.patch in rest.patch
> twice with different line numbers for the change.

Hmm, I just tried this myself and got the expected results -- the entire
original patch with the single change removed.

Sounds like it depends on the input you give it.  One thing that *might*
account for it is described in the 'BUGS' section of the interdiff man
page:

  There are some sets of patches in which there is just not enough
  information to produce a proper interdiff. In this case, the strategy
  employed is to revert the original patch and apply the new patch.
  This, unfortunately, means that interdiffs are not guaranteed to be
  reversible.

Do you think it could be that?

Tim.
*/


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