Try as I might, I have not found any way to launch a three-way comparison with EGit. The synchronize view seems to do it, but It seems to me that the "ancestor" of this comparison is always the "remote" side, which means that "synchronize workspace" will never detect any conflicts, even if there are some.
right-click > compare with > branch, tag... also does a two way comparison : left being the local version, right the other branch's... but no common ancestor is taken into account, thus no conflict detection there either.
Is there any reason for this choice? Is this something that is meant to evolve later on? Or is there something I've missed ?