Merge pull request #55353 from david-mcmahon/eliminate-version-updates

Automatic merge from submit-queue (batch tested with PRs 55265, 54092, 55353, 53733, 55385). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

Capture git export-subst strings in version.sh for 'git archive' use.

Eliminate the need to update pkg/version/base.go on release branch tagging.

This excellent solution brought to you by @ixdy.

 - [ ] Cherrypick to release-1.8
 - [ ] Cherrypick to release-1.7
 - [ ] Cherrypick to release-1.6?
 - [ ] Update kubernetes/release/anago to skip updating base.go files

ref kubernetes/release#459
ref #16815 (somewhat related)
cc @javier-b-perez

Kubernetes-commit: 4e68d2511ef07428a69a2b6c66efc2b05f4b97dc

pkg/version/base.go

@@ -51,9 +51,13 @@ var (
 	// semantic version is a git hash, but the version itself is no
 	// longer the direct output of "git describe", but a slight
 	// translation to be semver compliant.
+
+	// NOTE: The $Format strings are replaced during 'git archive' thanks to the
+	// companion .gitattributes file containing 'export-subst' in this same
+	// directory.  See also https://git-scm.com/docs/gitattributes
 	gitVersion   string = "v0.0.0-master+$Format:%h$"
-	gitCommit    string = "$Format:%H$"    // sha1 from git, output of $(git rev-parse HEAD)
-	gitTreeState string = "not a git tree" // state of git tree, either "clean" or "dirty"
+	gitCommit    string = "$Format:%H$" // sha1 from git, output of $(git rev-parse HEAD)
+	gitTreeState string = ""            // state of git tree, either "clean" or "dirty"
 
 	buildDate string = "1970-01-01T00:00:00Z" // build date in ISO8601 format, output of $(date -u +'%Y-%m-%dT%H:%M:%SZ')
 )