Importer sometimes creates merge proposals with an empty diff

[Max Bowsher]

See duplicates.

[Max Bowsher (maxb)]

Looking at the apt example referenced in a duplicate, I'm conjecturing the following possible sequence of events:

There's an upload to natty-proposed, which gets imported.
That upload somehow also ends up pulled in the oneiric branch, despite never actually being published in oneiric (?how?).
Then there's an actual upload to oneiric, but including the changelog history referencing the above natty-proposed version. The natty-proposed version gets collided out of the mainline of the oneiric branch, but then added back in as a merge.
When the importer goes to file the MP, the collision side branch is already fully within the ancestry of the target branch, so the diff is empty.

It seems to me that there's a class of genuine collision when we can prove require no further action - those when the debian/changelog entries give us sufficient cause for the existing import logic to add the collided content as a merge parent.

To avoid creating spurious MPs in these cases, I suggest we should check whether the collision side branch is within the ancestry of the target branch before filing MPs, and simply skip reporting the collision at all if that is the case.

[Martin Pool (mbp)]

On 2 June 2011 09:45, Max Bowsher <email address hidden> wrote:
> To avoid creating spurious MPs in these cases, I suggest we should check
> whether the collision side branch is within the ancestry of the target
> branch before filing MPs, and simply skip reporting the collision at all
> if that is the case.

That makes sense. Though I do wonder why Launchpad itself is not
suppressing the mp in this case...

[James Westby (james-w)]

On Wed, 01 Jun 2011 23:45:57 -0000, Max Bowsher <email address hidden> wrote:
> To avoid creating spurious MPs in these cases, I suggest we should check
> whether the collision side branch is within the ancestry of the target
> branch before filing MPs, and simply skip reporting the collision at all
> if that is the case.

That sounds like a reasonable check to me. Given that there is no action
to be taken I'm not sure why we would ever care to see these.

Thanks,

James