Fix local time when TZ is not set (#1649)

Do not override time.Local when TZ is empty or unset. It is already set correctly by go standard library.

pkg/lib/time.go

@@ -16,6 +16,9 @@ import (
 // statement does 'ENV["TZ"] = Asia/Istanbul'.
 func SetTZFromEnv() error {
 	tzenv := os.Getenv("TZ")
+	if tzenv == "" {
+		return nil
+	}
 	location, err := time.LoadLocation(tzenv)
 	if err != nil {
 		return fmt.Errorf("TZ environment variable appears malformed: \"%s\"", tzenv)