Set up p2.mirrorsURL property in result sites

[lcaron]

Copy of https://bugs.eclipse.org/bugs/show_bug.cgi?id=373059

As per http://dev.eclipse.org/mhonarc/lists/cross-project-issues-dev/msg07400.html

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Johannes Faltermeier:

Hi,
I may have a look. I know that a lot of projects use https://wiki.eclipse.org/WTP/Releng/Tools/addRepoProperties for this.
But as this needs the information where the update site is uploaded to, I have to check how to integrate it with the current
build/build jobs

Johannes Faltermeier:

Yes, but today I finally found some time to work on this.
I have a first isolated draft that takes an existing p2 repository and creates a new repository including the p2.mirrorURL:
jfaltermeier@4fc44fa
This could run as part of the release job:

1. "Mirror" the p2 repository to publish
2. add p2 mirrorURL and recreate p2 repository
3. upload this new repository

We could also change the regular build to (optionally) add the mirror urls. However this way one has to know that this build will be uploaded and where it will be uploaded to, so that the correct metadata is added.
Having wrong mirrorURLs is worse than having none at all as far as I know.

Problem with the approach on above branch is, that the category.xml is copied and the urls for the target platform as well. So this should be more closely aligned to the actual build to avoid overhead on release day.

[lcaron]

There is no activity on this bug, so I close it.