Commit both the liquibase xml file and code changes simultaneously to the subversion repository.
Never ever change a changeset! (Well, almost never)
Once you commit something to a branch, you should assume that another developer has already checked out your code and applied the database changes! Therefore, you should not just go and modify a changeset! Instead you should add another changeset below the previous one that does the necessary modifications. That way no developers have to go and mess with their database to get the changesets to apply.
If Repair the changeset by adding a later changeset (with a different "id") is the preferred approach. But if a changeset contains an error , that you obviously must change it. However, you should change the liquibase changeset "id" on the element when you do so to prevent errors with other developerscorrect, follow the instructions on ?How to modify a bad changeset.
Preconditions are important