Sort config files as documented.

command/agent/config.go

@@ -8,6 +8,7 @@ import (
 	"os"
 	"path/filepath"
 	"runtime"
+	"sort"
 	"strings"
 	"time"
 
@@ -705,6 +706,8 @@ func LoadConfigDir(dir string) (*Config, error) {
 		return &Config{}, nil
 	}
 
+	sort.Strings(files)
+
 	var result *Config
 	for _, f := range files {
 		config, err := LoadConfigFile(f)