patch subtraction bug

[Eli Carter]

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.

When I tried the same abuse, but filtering only on file (no --hunks=),
combinediff removed that file's deltas from the original diff, just as I
hoped it would.

So it looks to me like combinediff isn't accounting for the change in line
numbers for a file due to one patch that affects the target line numbers
in the other patch.

If I have a chance, I'll look at the code and try to make this work, but
it'll be another day.

Have fun,

Eli
eli.carter@commprove.com