Name all three forms git describe gives for the version

README, script/version and the version test's header said git describe
gives the tag or the short commit. On a commit after a tag it gives the
tag, the commits since it and the short commit; each place now names
that case too.

Model: opus-5-5

script/version

@@ -7,7 +7,9 @@
 #   1. $VERSION, if set and not empty: an explicit value, such as the
 #      Dockerfile's VERSION build arg.
 #   2. If this checkout has .git, `git describe --tags --always`: the tag
-#      on a tagged commit, otherwise the short commit.
+#      on a tagged commit; the tag, the commits since it and the short
+#      commit on a later commit (v1.2.3-4-gabc1234); the short commit when
+#      no tag is reachable.
 #   3. Otherwise, as in a source tarball, the version package.json declares.
 #
 # A checkout with .git whose version still comes out empty, dev or unknown