My problem:
I'm working on a project where upstream doesn't use source control of any sort. Yes, that's exactly the same reaction I had as well.
I keep track of their releases on a branch named upstream. When new releases are made, I add them to this branch as a single commit, so at least I know what changed (in bulk) from the last release.
My changes (usually!) end up in the official releases, but because they don't use source control, my commits never do. Hence I want to find all the commits I've made since the last merge, as an "approximation" of what's changed between my release and theirs. Simple git log A..B isn't what I want here.
So, here's the network graph. I want to find the last point on master where upstream was merged in. In this case, that's 9039b22b .