Fix BuildConfigInstantiateFailed warning when lastVersion == 0

Build config instatiate should not emit a warning when
bc.Status.LastVersion != lastVersion and lastVersion == 0
Fixes #16557

pkg/build/generator/generator.go

@@ -314,9 +314,9 @@ func (g *BuildGenerator) instantiate(ctx apirequest.Context, request *buildapi.B
 }
 
 // checkBuildConfigLastVersion will return an error if the BuildConfig's LastVersion doesn't match the passed in lastVersion
-// when lastVersion is not nil
+// when lastVersion is not nil and lastVersion is not zero
 func (g *BuildGenerator) checkLastVersion(bc *buildapi.BuildConfig, lastVersion *int64) error {
-	if lastVersion != nil && bc.Status.LastVersion != *lastVersion {
+	if lastVersion != nil && *lastVersion != 0 && bc.Status.LastVersion != *lastVersion {
 		glog.V(2).Infof("Aborting version triggered build for BuildConfig %s/%s because the BuildConfig LastVersion (%d) does not match the requested LastVersion (%d)", bc.Namespace, bc.Name, bc.Status.LastVersion, *lastVersion)
 		return fmt.Errorf("the LastVersion(%v) on build config %s/%s does not match the build request LastVersion(%d)",
 			bc.Status.LastVersion, bc.Namespace, bc.Name, *lastVersion)

pkg/build/generator/generator_test.go

@@ -596,9 +596,16 @@ func TestInstantiateWithLastVersion(t *testing.T) {
 		t.Errorf("Unexpected error %v", err)
 	}
 
-	// Version specified, but doesn't match
+	// Version 0 specified, but doesn't match
 	lastVersion = 0
 	_, err = g.Instantiate(apirequest.NewDefaultContext(), &buildapi.BuildRequest{LastVersion: &lastVersion})
+	if err != nil {
+		t.Errorf("Unexpected error %v", err)
+	}
+
+	// Version specified, but doesn't match
+	lastVersion = int64(2)
+	_, err = g.Instantiate(apirequest.NewDefaultContext(), &buildapi.BuildRequest{LastVersion: &lastVersion})
 	if err == nil {
 		t.Errorf("Expected an error and did not get one")
 	}