Moving Git repository content to another repository preserving history

I think the commands you are looking for are:

cd repo2
git checkout master
git remote add r1remote **url-of-repo1**
git fetch r1remote
git merge r1remote/master --allow-unrelated-histories
git remote rm r1remote

After that repo2/master will contain everything from repo2/master and repo1/master, and will also have the history of both of them.

Perfectly described here https://www.smashingmagazine.com/2014/05/moving-git-repository-new-server/

First, we have to fetch all of the remote branches and tags from the existing repository to our local index:

git fetch origin

We can check for any missing branches that we need to create a local copy of:

git branch -a

Let’s use the SSH-cloned URL of our new repository to create a new remote in our existing local repository:

git remote add new-origin [email protected]:manakor/manascope.git

Now we are ready to push all local branches and tags to the new remote named new-origin:

git push --all new-origin 
git push --tags new-origin

Let’s make new-origin the default remote:

git remote rm origin

Rename new-origin to just origin, so that it becomes the default remote:

git remote rename new-origin origin

If you're looking to preserve the existing branches and commit history, here's one way that worked for me.

git clone --mirror https://github.com/account/repo.git cloned-repo
cd cloned-repo
git push --mirror {URL of new (empty) repo}

# at this point only remote cloned-repo is correct, local has auto-generated repo structure with folders such as "branches" or "refs"
cd ..
rm -rf cloned-repo
git clone {URL of new (empty) repo}
# only now will you see the expected user-generated contents in local cloned-repo folder

# note: all non-master branches are avaialable, but git branch will not show them until you git checkout each of them
# to automatically checkout all remote branches use this loop:
for b in `git branch -r | grep -v -- '->'`; do git branch --track ${b##origin/} $b; done

Now, suppose you want to keep the source and destination repos in sync for a period of time. For example, there's still activity within the current remote repo that you want to bring over to the new/replacement repo.

git clone -o old https://github.com/account/repo.git my-repo
cd my-repo
git remote add new {URL of new repo}

To pull down the latest updates (assuming you have no local changes):

git checkout {branch(es) of interest}
git pull old
git push --all new

NB: I have yet to use submodules, so I don't know what additional steps might be required if you have them.