https://gitlab.gnome.org/GNOME/libxml2/merge_requests/14

From 54878c018af979b20ca1bfbf12599973484cae5b Mon Sep 17 00:00:00 2001
From: Mike Frysinger <vapier@gentoo.org>
Date: Thu, 3 Jan 2019 05:44:03 -0500
Subject: [PATCH] fix reader5.py test when building out of tree

When building out of tree, the relative path this test uses doesn't
work.  Resolve the path relative to the test script itself instead.

Url: https://bugs.gentoo.org/565576
--- a/python/tests/reader5.py
+++ b/python/tests/reader5.py
@@ -4,6 +4,7 @@
 # this extract the Dragon bibliography entries from the XML specification
 #
 import libxml2
+import os
 import sys
 
 # Memory debug specific
@@ -14,7 +15,8 @@ Ravi Sethi, and Jeffrey D. Ullman.
 <emph>Compilers:  Principles, Techniques, and Tools</emph>.
 Reading:  Addison-Wesley, 1986, rpt. corr. 1988.</bibl>"""
 
-f = open('../../test/valid/REC-xml-19980210.xml', 'rb')
+basedir = os.path.dirname(os.path.realpath(__file__))
+f = open(os.path.join(basedir, '../../test/valid/REC-xml-19980210.xml'), 'rb')
 input = libxml2.inputBuffer(f)
 reader = input.newTextReader("REC")
 res=""