All repositories that had not been migrated before the shutdown of alioth are still available at the alioth archive. There you can find a compressed tarfile of the bare repository.
So to move such a repository to salsa …
- … create the new repository on salsa
- … download your file from alioth-archive
wget https://alioth-archive.debian.org/git/debian-iot/duktape.git.tar.xz - … unpack it
tar -Jxf duktape.git.tar.xz - … cd to your bare repository
cd duktape.git - … push your repository to salsa
git push --mirror git@salsa.debian.org:debian-iot-team/duktape.git
Voila, your new repository is ready to be used.