It is absolutely possible to do this in git. It helps if you forget about "files" as something to "move".
I did it in the project I'm working on now! It originally had one main repository, and another for an extension that was used as a git submodule in the main one. Active development proceeded in both, with shitloads of commits in the main one just to update the reference to the submodule.
I decided this was retarded, so I took a clone of the extension repository, used filter-branch to rewrite it's entire history so that all the paths were always prefixed with "vendor/extensions/project_name/", and pushed it as an unrelated branch into the main repository.
Then in the main repository I made a new branch, removed the old submodule junk there, did a nice clean merge that melded all the commits from the extension branch going back in time, and made that the new master branch.
I did it in the project I'm working on now! It originally had one main repository, and another for an extension that was used as a git submodule in the main one. Active development proceeded in both, with shitloads of commits in the main one just to update the reference to the submodule.
I decided this was retarded, so I took a clone of the extension repository, used filter-branch to rewrite it's entire history so that all the paths were always prefixed with "vendor/extensions/project_name/", and pushed it as an unrelated branch into the main repository.
Then in the main repository I made a new branch, removed the old submodule junk there, did a nice clean merge that melded all the commits from the extension branch going back in time, and made that the new master branch.