fix: throw away unknown version

See toolshed/abra#715

pkg/app/app.go

@@ -633,6 +633,11 @@ func (a App) WipeRecipeVersion() error {
 
 // WriteRecipeVersion writes the recipe version to the app .env file.
 func (a App) WriteRecipeVersion(version string, dryRun bool) error {
+	if version == config.UNKNOWN_DEFAULT {
+		log.Debug(i18n.G("version is unknown, skipping env write"))
+		return nil
+	}
+
 	file, err := os.Open(a.Path)
 	if err != nil {
 		return err

pkg/app/app_test.go

@@ -224,3 +224,16 @@ func TestWriteRecipeVersionOverwrite(t *testing.T) {
 
 	assert.Equal(t, "foo", app.Recipe.EnvVersion)
 }
+
+func TestWriteRecipeVersionUnknown(t *testing.T) {
+	app, err := appPkg.GetApp(testPkg.ExpectedAppFiles, testPkg.AppName)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if err := app.WriteRecipeVersion(config.UNKNOWN_DEFAULT, false); err != nil {
+		t.Fatal(err)
+	}
+
+	assert.NotEqual(t, config.UNKNOWN_DEFAULT, app.Recipe.EnvVersion)
+}