To transfer using git, you must commit the changes to the local repo on computer A. If you do not want to do this, you just need to copy the changed files from computer A to computer B outside of git.
If both computers have access to the central git repository, which you can do, as others suggest, and transfer the code to a new branch on computer A, push the new branch to the central repo, and then pull the new branch down to computer B.
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, sneakernet, git bundles A B.
A, git format-patch , B git apply .