Merge conflicts resolve using mine rather than theirs (and vice-versa)

It seems to me that if I have a merge conflict and I select "Resolve Using Theirs..." source tree actually resolves using my changes, and if I select "Resolve Using Mine..." source tree actual resolves using theirs!

See: https://answers.atlassian.com/questions/180870/merge-conflicts-resolve-using-theirs-vs-mine