Merge changes of copied repository without true common ancestor in git
问题 I have a project, DemoA that was built off of a git repository, Project1. Unfortunately, DemoA started as simply a copy of the files from Project1, before itself turning into an actual long-term project. I would now like to make Project1 a submodule of DemoA, but - more importantly - want to merge in the changes done on the code derived from Project1, in DemoA. I have done a subtree split on DemoA to create a branch P1, which has all the changes done to the Project1 codebase in DemoA. I have