modifying libva (master) .gitignore

[Nicholas D Steeves]

Hi Sebastian,

On 5 July 2016 at 05:30, Sebastian Ramacher <sramacher at debian.org> wrote:
>
> On 2016-07-04 14:54:17, Nicholas D Steeves wrote:
>> I ran into an issue with backporting libva.  Is it ok if I add the
>> following to libva (master) .gitignore?:
>>
>> debian.upstream/changelog
>> debian.upstream/control
>
> How will this change affect gbp import-orig since these files come from the
> upstream tarball?
>
> I usually use --git-ignore-new and cases where I really need gbp buildpackage.
>

I've read the following article:
https://wiki.debian.org/UpstreamGuide

>From what I understand of that page, and what I understand of the
build process, it should be safe and desirable to prevent the
debian.upstream/* from being imported into (master), because we use
the ones in the (master) libva/debian.  Debian.upstream should
probably still be imported into the (upstream) branch.

Today I a tested a variety of approaches in combination with gbp
import-orig, and it seems like this simple .gitignore solution might
not be viable.  For example, adding debian.upstream to .gitignore and
then deleting debian.upstream will produce conflicts whenever gbp
import-orig imports a new version.  Alternatively, if debian.upstream
is not deleted then the directory on Alioth will increasingly get
stale.  I think this is probably the correct solution:

https://git-scm.com/book/en/v2/Customizing-Git-Git-Attributes#Merge-Strategies
more documentation available here:
https://git-scm.com/docs/gitattributes

I have to take a break from this for a couple hours, but it looks like
setting a custom attribute of merge=ours (deleted) for the
debian.upstream directory will prevent both the merge conflict every
time gbp import-orig is run, and will prevent the stale directory on
Alioth by maintaining its deleted state.

Two questions:  What do you think of this approach?  If we go ahead
with this, on specifically what page should we document this "using
git attributes in Debian packaging to prevent import of upstream
debian directory" approach so that other Debian developers can refer
to it?  It would have saved me a tonne of time if I had been able to,
for example, find this information in:
https://wiki.debian.org/PackagingWithGit

Kind regards,
Nicholas