Skip loading pipelines when loading async MR diffs
I noticed this when looking at http://profiler.gitlap.com/20170620/6f56f201-0625-4893-b599-7bbe219a5542.html.gz - I'm pretty sure we don't need the pipelines on this action? And loading them can be really expensive.
If we do, please tell me, or maybe the pipelines will tell us.
If we don't, maybe we should include this in a 9.3 patch?