Add guard in test_issue_547.py to skip when not a debug build.

tests/bugfixes/github/test_issue_547.py

@@ -1,11 +1,14 @@
 # -*- coding: utf-8 -*-
 
 from system_tests import CaseMeta, path
+import unittest
+
+@unittest.skip("Skipping test using option -pR (only for Debug mode)")
 
 class test_issue_547(metaclass=CaseMeta):
     """
     Regression test for the bug described in:
-    https://github.com/Exiv2/exiv2/pull/960
+    https://github.com/Exiv2/exiv2/pull/547
     """
     url = "https://github.com/Exiv2/exiv2/issues/547"