At some point in the past I tagged a revision in my local clone so that I
could easily run diffs against that initial state.

Now "git describe --tags" returns that tag name, which ends up in
$ZSH_PATCHLEVEL, which is not correct. "git fetch --tags" does not change
this.

However, "git tag --delete $(git describe --tags)" says "tag not found".  I
don't know how it's possible for describe to return a tag that doesn't
exist, or how it got that way, but here I am.

How do I get rid of that tag?  I've read the doc for "git fetch --prune
--prune-tags" but that sounds as if it'll remove other local references
that don't exist on the origin, which is not what I want.

Google search is not helping.  Thanks.