Fix #1342 replace intrasite links also in summary metadata

Thanks to @Chimrod for pointing this out.

pelican/contents.py

@@ -278,7 +278,8 @@ class Content(object):
         content.
         """
         if hasattr(self, '_summary'):
-            return self._summary
+            return self._update_content(self._summary,
+                                        self._context.get('localsiteurl', ''))
 
         if self.settings['SUMMARY_MAX_LENGTH'] is None:
             return self.content

pelican/tests/test_contents.py

@@ -287,6 +287,19 @@ class TestPage(unittest.TestCase):
             '?utm_whatever=234&highlight=word#section-2">link</a>'
         )
 
+        # also test for summary in metadata
+        args['metadata']['summary'] = (
+            'A simple summary test, with a '
+            '<a href="|filename|article.rst">link</a>'
+        )
+        args['context']['localsiteurl'] = 'http://notmyidea.org'
+        p = Page(**args)
+        self.assertEqual(
+            p.summary,
+            'A simple summary test, with a '
+            '<a href="http://notmyidea.org/article.html">link</a>'
+        )
+
     def test_intrasite_link_more(self):
         # type does not take unicode in PY2 and bytes in PY3, which in
         # combination with unicode literals leads to following insane line: