When making relative URIs absolute, use the parent as the relative

root when the context is not folderish.  Fixes an issue where relative
URLs from Plone 3, for example, had the wrong URLs under Plone 4 when
a default page was used for a folder.

I had test failures locally before this change but this change
introduced no more failures.  Sorry I can't do better than that.

CHANGES.txt

@@ -4,6 +4,12 @@ Changelog
 1.2 - unreleased
 ----------------
 
+- When making relative URIs absolute, use the parent as the relative
+  root when the context is not folderish.  Fixes an issue where
+  relative URLs from Plone 3, for example, had the wrong URLs under
+  Plone 4 when a default page was used for a folder.
+  [rossp]
+
 - Fixed testing error when packaged with a missing README.rst.
   [maurits]
 

plone/outputfilters/filters/resolveuid_and_caption.py

@@ -1,5 +1,5 @@
 from ZODB.POSException import ConflictError
-from Acquisition import aq_base, aq_acquire
+from Acquisition import aq_base, aq_acquire, aq_parent
 from zExceptions import NotFound
 from zope.publisher.interfaces import NotFound as ztkNotFound
 from DocumentTemplate.DT_Util import html_quote
@@ -309,8 +309,12 @@ def unknown_starttag(self, tag, attrs):
                     elif resolveuid_re.match(href) is None:
                         # absolutize relative URIs; this text isn't necessarily
                         # being rendered in the context where it was stored
-                        href = urljoin(self.context.absolute_url() + '/',
-                                       subpath) + appendix
+                        relative_root = self.context
+                        if not getattr(
+                            self.context, 'isPrincipiaFolderish', False):
+                            relative_root = aq_parent(self.context)
+                        actual_url = relative_root.absolute_url()
+                        href = urljoin(actual_url + '/', subpath) + appendix
                     attributes['href'] = href
                     attrs = attributes.iteritems()
             elif tag == 'img':