Don't process metadata links before all files are present.

The refresh_metadata_intersite_links() is called again later, so this
bit was only causing everything to be processed twice. Besides
that, it makes the processing dependent on file order -- in particular,
when metadata references a file that was not parsed yet, it reported an
"Unable to find" warning. But everything is found in the second pass, so
this only causes a superflous false warning and no change to the output.

The related test now needs to call the
refresh_metadata_intersite_links() explicitly. That function is called
from Pelican.run() and all generators but the test processes just one
page so it has no chance of being called implicitly.

Related discussion: https://github.com/getpelican/pelican/pull/2288/files#r204337359

pelican/contents.py

@@ -142,10 +142,6 @@ class Content(object):
         if not hasattr(self, 'status'):
             self.status = getattr(self, 'default_status', None)
 
-        if (len(self._context.get('generated_content', [])) > 0 or
-                len(self._context.get('static_content', [])) > 0):
-            self.refresh_metadata_intersite_links()
-
         signals.content_object_init.send(self)
 
     def __str__(self):

pelican/tests/test_contents.py

@@ -333,6 +333,10 @@ class TestPage(LoggedTestCase):
         args['metadata']['custom'] = parsed
         args['context']['localsiteurl'] = 'http://notmyidea.org'
         p = Page(**args)
+        # This is called implicitly from all generators and Pelican.run() once
+        # all files are processed. Here we process just one page so it needs
+        # to be called explicitly.
+        p.refresh_metadata_intersite_links()
         self.assertEqual(p.summary, linked)
         self.assertEqual(p.custom, linked)