[gtk-doc] mkdb: fix more porting errors

[Stefan Sauer <stefkost src gnome org>]

commit 819fb337216abe5e209136e690b57d2411df7674
Author: Stefan Sauer <ensonic users sf net>
Date:   Sun May 14 21:16:39 2017 +0200

    mkdb: fix more porting errors

 gtkdoc-mkdb.in |    6 +++++-
 1 files changed, 5 insertions(+), 1 deletions(-)
---
diff --git a/gtkdoc-mkdb.in b/gtkdoc-mkdb.in
index c8c656e..c988a49 100755
--- a/gtkdoc-mkdb.in
+++ b/gtkdoc-mkdb.in
@@ -2804,7 +2804,11 @@ def ExpandAbbreviationsEndTag(start_tag):
     if start_tag == "<!DOCTYPE":
         return '>'
     m = re.search(r'<(\w+)', start_tag)
-    return "</%s>" % m.group(1)
+    if m:
+        return "</%s>" % m.group(1)
+
+    logging.warning('no end tag for "%s"', start_tag)
+    return ''
 
 # Called inside or outside each CDATA or <programlisting> section.
 def ExpandAbbreviationsCallback(text, symbol, tag):