How can I find out if there were conflicts when merging a branch and what shenanigans did the person have to do to resolve those conflicts?
git log -p seems to show empty diffs for all merge commits, regardless whether they have manual changes or not.
git show produces a combined diff for a merge commit by default, which will contain only the lines that changed as part of the conflict resolution.
git show <merge_commit_sha1>
git log takes the --cc option to produce combined diffs for merge commits. For example, to find all merge commits with manual changes you can use:
git log -p --cc --min-parents=2
and look for commits with diffs.