Please avoid noisy merge commits in frameworks

[Stephen Kelly]

Hi there,

I was reviewing the changes in the frameworks branch from yesterday. 
Something I noticed was that there are a lot of merge commits that don't 
need to exist.

Please use `gitk` to see them.

The unneeded merge commits actually make it harder to follow frameworks for 
me. It breaks things like using `gitk --first-parent` which should show only 
the commits in frameworks. If you now try that out, you will see that the 
people who made the unneeded merges actually hide commits from the people 
that didn't. See for example that if you run `gitk --first-parent` commit 
011b6115d2dd91e9104095f3a5065e80009ea1a7 from David is not shown.

This is also the reason you should not cherry-pick from 4.8 into frameworks 
by the way. If you cherry-pick, then 4.8 commits show up in `gitk --first-
parent` when trying to look at only the frameworks branch. That means they 
are just noise, so please keep that in mind too.

To help out:

* Do not use git pull when working on frameworks. Use git pull --rebase 
instead.

* Alternatively (preffered) configure git to always add an implicit --rebase 
to the pull command:
http://d.strelau.net/post/47338904/git-pull-rebase-by-default

* Use gitk --all to see what would happen if you push. You should never have 
to create merge commits. If you do, then please clean it up before pushing.

Thanks,

Steve.