Push tag from shallow clone?

The documentation for git clone says that if you use --depth=1 to make a shallow clone that you can't push it. But I made a shallow clone, created a tag, then tried to push that tag and it worked. Am I just getting lucky or is it safe to push a tag with a shallow clone?

The reason I ask is that we have an automatic builder/tester/archiver where I'd like to make a shallow clone (to save space since it only needs the tip of the branch to do the build), do the normal build and test and if it all passes, tag it, and push the tag so people can pull tags that have been verified by the automated builder.