pr feedback

main.go

@@ -56,7 +56,9 @@ type GAE struct {
 	// MaxVersions is an optional value that can be used along with the "deploy" or
 	// "update" actions. If set to a non-zero value, the plugin will look up the versions
 	// of the deployed service and delete any older versions beyond the "max" value
-	// provided.
+	// provided. If any of the "older" versions that should be deleted is actually
+	// serving traffic, they will not be deleted. This may result in the actual version
+	// count being higher than the max listed here.
 	MaxVersions int `json:"max_versions"`
 
 	// CronFile is the name of the cron.yaml file to use for this deployment. This field

remove.go

@@ -33,7 +33,7 @@ func removeOldVersions(runner *Environ, workspace string, vargs GAE) error {
 		service = appStruct.Module
 	}
 
-	// look  up existing versions for given service ordered by create time desc
+	// look up existing versions for given service ordered by create time desc
 	var versionJSON bytes.Buffer
 	sout := runner.stdout
 	runner.stdout = &versionJSON
@@ -61,6 +61,11 @@ func removeOldVersions(runner *Environ, workspace string, vargs GAE) error {
 		}
 		toDelete = append(toDelete, res.ID)
 	}
+
+	if len(toDelete) == 0 {
+		return nil
+	}
+
 	log.Printf("deleting %d versions: %s", len(toDelete), toDelete)
 
 	runner.stdout = sout