Increase depth of shallow clone without fetching other branches

Question

To save disk space, I generally shallow clone:

• The latest remote git tag

• The default branch with:

  git clone --depth 20 --shallow-submodules --recurse-submodules

How do I increase increase the depth of a shallow clone?

Note: I don't want to increase to a full clone, I want to deepen only what I already have.

Answer 1

Use git fetch --deepen=<depth>:

man git-fetch says:

  --deepen=<depth>
       Similar to --depth, except it specifies the number of commits from
       the current shallow boundary instead of from the tip of each remote
       branch history.

Answer 2

To avoid fetching other branches, just specify the remote and branch:

git fetch <remote_name> <branch_name> --deepen=<depth>

The command will fetch and add <depth> additional commits to the shallow clone.