Fix check for flag in case RELATIVE_PATHS should be changed somehow

src/Composer/Config.php

@@ -180,7 +180,7 @@ class Config
                     return $val;
                 }
 
-                return ($flags & self::RELATIVE_PATHS == 1) ? $val : $this->realpath($val);
+                return ($flags & self::RELATIVE_PATHS == self::RELATIVE_PATHS) ? $val : $this->realpath($val);
 
             case 'cache-ttl':
                 return (int) $this->config[$key];