Union-merging is insane and thus should take some insane understanding of what you're doing before you can do it. Anyone that's merging two unrelated repositori

Union-merging is insane and thus should take some insane understanding of what you're doing before you can do it. Anyone that's merging two unrelated repositories should understand what's going on under the hood anyways. What you're doing in git actually makes sense, since a normal pull is just fetch+checkout+merge+commit, you have to go into the plumbing and trick every step of the way to fetch, checkout, and merge using the wrong repositories. In the future, this could be made porcelain as it has been in hg, but do people really want to do this? It's much safer and saner to use submodules for 99% of use cases.