Fix warnings when some code reuses the phpvfscomposer:// stream wrapp…

…er to try and access other files, refs #10387

src/Composer/Installer/BinaryInstaller.php

@@ -355,7 +355,12 @@ public function stream_set_option(\$option, \$arg1, \$arg2)
 
             public function url_stat(\$path, \$flags)
             {
-                return stat(substr(\$path, 17));
+                \$path = substr(\$path, 17);
+                if (file_exists(\$path)) {
+                    return stat(\$path);
+                }
+
+                return false;
             }
         }
     }