fix(internal/librarian): ignore retracted tags when report version (#3063)

Introduce a hardcoded list of retracted versions and use pseudo-version
string instead.
It's less ideal that we keep this hardcoded apart from go.mod record.
But consider retracted versions are should be fairly rare, this should
be acceptable.

**The issue:**
v1.0.0 and v1.0.1 was previously retracted and added to go.mod retract
list in #2904. These tags
are still present, this caused problem to `version` command as
`info.Main.Versio` is determined during `go build` and for local builds,
it would end up prefix with "v1.0.2-".
Note, this problem only occurs for local dev builds from untagged
commits. If you run version command from v0.7.0, it correctly prints the
version.


**Alternative approaches considered:**
   -   **Runtime `go.mod` parsing**: This makes the binary fragile. 
the binary dependent on the presence and structure of `go.mod` at
runtime,
       not the best practice.
- **`go generate` for retraction list**: Create a build-time script that
reads go.mod and automatically generates a Go source file containing the
list of retracted versions. The complexity of this setup and parsing
logic seems overkill for these rare occurrences.
- **delete retracted tags and `git fetch --prune`**: Not best practice
as it's a destructive action that rewrites history.

Fix #3048

Author: zhumin8

internal/librarian/version.go

@@ -24,6 +24,11 @@ import (
 //go:embed version.txt
 var versionString string
 
+// retractedVersions is a list of Go module versions that have been officially retracted
+// via the go.mod 'retract' directive. v1.0.2 added to account for local dev builds
+// from untagged commits.
+var retractedVersions = []string{"v1.0.0", "v1.0.1", "v1.0.2"}
+
 // Version return the version information for the binary, which is constructed
 // following https://go.dev/ref/mod#versions.
 func Version() string {
@@ -35,10 +40,24 @@ func Version() string {
 }
 
 func version(info *debug.BuildInfo) string {
-	if info.Main.Version != "" && info.Main.Version != "(devel)" {
-		return info.Main.Version
+	isRetracted := false
+	for _, v := range retractedVersions {
+		if strings.HasPrefix(info.Main.Version, v) {
+			isRetracted = true
+			break
+		}
+	}
+	// A pseudo-version should be used for retracted versions or for
+	// development builds that don't have a proper version tag.
+	isDevelBuild := info.Main.Version == "" || info.Main.Version == "(devel)"
+	if isRetracted || isDevelBuild {
+		return newPseudoVersion(info)
 	}
+	return info.Main.Version
+}
 
+// newPseudoVersion constructs a pseudo-version string from the build info.
+func newPseudoVersion(info *debug.BuildInfo) string {
 	var revision, at string
 	for _, s := range info.Settings {
 		if s.Key == "vcs.revision" {
@@ -52,7 +71,6 @@ func version(info *debug.BuildInfo) string {
 	if revision == "" && at == "" {
 		return "not available"
 	}
-
 	// Construct the pseudo-version string per
 	// https://go.dev/ref/mod#pseudo-versions.
 	var buf strings.Builder

internal/librarian/version.txt

@@ -1 +1 @@
-0.2.0
+0.7.0

internal/librarian/version_test.go

@@ -90,6 +90,32 @@ func TestVersion(t *testing.T) {
 			want:      "not available",
 			buildinfo: &debug.BuildInfo{},
 		},
+		{
+			name: "retracted version, build from tagged commit",
+			want: fmt.Sprintf("%s-123456789000-20230125195754", baseVersion),
+			buildinfo: &debug.BuildInfo{
+				Main: debug.Module{
+					Version: "v1.0.0",
+				},
+				Settings: []debug.BuildSetting{
+					{Key: "vcs.revision", Value: "1234567890001234"},
+					{Key: "vcs.time", Value: "2023-01-25T19:57:54Z"},
+				},
+			},
+		},
+		{
+			name: "retracted version, local dev builds from untagged commits",
+			want: fmt.Sprintf("%s-123456789000-20230125195754", baseVersion),
+			buildinfo: &debug.BuildInfo{
+				Main: debug.Module{
+					Version: "v1.0.2-0.20251125150633-68dcc1cc4ab4+dirty",
+				},
+				Settings: []debug.BuildSetting{
+					{Key: "vcs.revision", Value: "1234567890001234"},
+					{Key: "vcs.time", Value: "2023-01-25T19:57:54Z"},
+				},
+			},
+		},
 	} {
 		t.Run(test.name, func(t *testing.T) {
 			if got := version(test.buildinfo); got != test.want {