Adds exception for data-dir check in -dev mode.

This was changed in #2529.

command/agent/command.go

@@ -205,8 +205,9 @@ func (c *Command) readConfig() *Config {
 		config.SkipLeaveOnInt = Bool(config.Server)
 	}
 
-	// Ensure we have a data directory
-	if config.DataDir == "" && !dev {
+	// Ensure we have a data directory if we are not in dev mode.
+	if !dev {
+		if config.DataDir == "" {
 			c.Ui.Error("Must specify data directory using -data-dir")
 			return nil
 		}
@@ -218,6 +219,7 @@ func (c *Command) readConfig() *Config {
 			c.Ui.Error(fmt.Sprintf("The data-dir specified at %q is not a directory", config.DataDir))
 			return nil
 		}
+	}
 
 	// Ensure all endpoints are unique
 	if err := config.verifyUniqueListeners(); err != nil {