[OE-core] using devtool for rebasing patches

[Alexander Kanavin]

Hello Paul,

it would be very useful if devtool offered support for rebasing source 
patches when they fail to apply, but currently there does not seem to be 
any such feature:

ak at kanavin-desktop:~/development/poky/build$ devtool modify libksba
Parsing recipes..done.
NOTE: Fetching libksba...
NOTE: Unpacking...
NOTE: Patching...
ERROR: Applying 'ksba-add-pkgconfig-support.patch' failed:
checking file Makefile.am
Hunk #1 FAILED at 21.
1 out of 1 hunk FAILED
checking file configure.ac
Hunk #1 succeeded at 414 (offset 14 lines).
checking file ksba.pc.in
checking file src/ksba.m4
ERROR: Function failed: patch_do_patch
ak at kanavin-desktop:~/development/poky/build$

What devtool could do here is apply the patches that can be applied and 
then partially apply the patches that fail. Then give the developer some 
kind of UI for dealing with the rejected hunks (which typically means 
finding the place in the target file where the changes should go and 
then manually editing them in, while looking at the original patch).

Without this feature devtool is half as useful as it could be 
particularly for recipe version updates.

Thanks,
Alex