REST API: cache secondary mf2 html fetches as well as primary

to handle errors like this:

```
Traceback (most recent call last):
...
File "app.py", line 150, in get
  mf2, fetch_mf2_func=lambda url: mf2py.parse(url=url))
File "microformats2.py", line 728, in find_author
  author = mf2util.find_author(parsed, 'http://123', **kwargs)
File ".../mf2util.py", line 300, in find_author
  parsed = fetch_mf2_func(author_page)
File "app.py", line 150, in <lambda>
  mf2, fetch_mf2_func=lambda url: mf2py.parse(url=url))
...
File ".../requests/packages/urllib3/contrib/appengine.py", line 109, in urlopen
  raise TimeoutError(self, e)
TimeoutError: (<requests.packages.urllib3.contrib.appengine.AppEngineManager object at 0xfb387410>, DeadlineExceededError('Deadline exceeded while waiting for HTTP response from URL: https://aaronparecki.com/',))
```

app.py

@@ -106,8 +106,37 @@ def get(self):
     if input not in expected_inputs:
       raise exc.HTTPBadRequest('Invalid input: %s, expected one of %r' %
                                (input, expected_inputs))
-    url = util.get_required_param(self, 'url')
+    url, body = self._urlopen(util.get_required_param(self, 'url'))
 
+    # decode data
+    mf2 = None
+    if input == 'html':
+      mf2 = mf2py.parse(doc=body, url=url)
+    elif input == 'json-mf2':
+      mf2 = json.loads(body)
+      mf2.setdefault('rels', {})  # mf2util expects rels
+
+    actor = None
+    title = None
+    if mf2:
+      def fetch_mf2_func(url):
+        _, doc = self._urlopen(url)
+        return mf2py.parse(doc=doc, url=url)
+      actor = microformats2.find_author(mf2, fetch_mf2_func=fetch_mf2_func)
+      title = mf2util.interpret_feed(mf2, url).get('name')
+
+    if input == 'activitystreams':
+      activities = json.loads(body)
+    elif input == 'html':
+      activities = microformats2.html_to_activities(body, url, actor)
+    elif input == 'json-mf2':
+      activities = [microformats2.json_to_object(item, actor=actor)
+                    for item in mf2.get('items', [])]
+
+    self.write_response(source.Source.make_activities_base_response(activities),
+                        url=url, actor=actor, title=title)
+
+  def _urlopen(self, url):
     # check if request is cached
     cache = self.request.get('cache', '').lower() != 'false'
     cache_key = 'U %s' % url
@@ -135,31 +164,7 @@ def get(self):
         logging.info('Caching response in %r', cache_key)
         memcache.set(cache_key, {'url': url, 'body': body}, URL_CACHE_TIME)
 
-    # decode data
-    mf2 = None
-    if input == 'html':
-      mf2 = mf2py.parse(doc=body, url=url)
-    elif input == 'json-mf2':
-      mf2 = json.loads(body)
-      mf2.setdefault('rels', {})  # mf2util expects rels
-
-    actor = None
-    title = None
-    if mf2:
-      actor = microformats2.find_author(
-        mf2, fetch_mf2_func=lambda url: mf2py.parse(url=url))
-      title = mf2util.interpret_feed(mf2, url).get('name')
-
-    if input == 'activitystreams':
-      activities = json.loads(body)
-    elif input == 'html':
-      activities = microformats2.html_to_activities(body, url, actor)
-    elif input == 'json-mf2':
-      activities = [microformats2.json_to_object(item, actor=actor)
-                    for item in mf2.get('items', [])]
-
-    self.write_response(source.Source.make_activities_base_response(activities),
-                        url=url, actor=actor, title=title)
+    return url, body
 
 
 application = webapp2.WSGIApplication([

test_app.py

@@ -193,12 +193,12 @@ def test_url_html_to_atom_rel_author(self):
 <a href="/author" rel="author"></a>,
 """
     })
-    self.expect_requests_get('http://my/author', """
+    self.expect_urlopen('http://my/author', """
 <div class="h-card">
   <a class="u-url" href="http://my/author">Someone Else</a>
   <img class="u-photo" src="http://someone/picture" />
 </div>
-""", headers=mox.IgnoreArg(), timeout=None)
+""", timeout=15)
     self.mox.ReplayAll()
 
     resp = app.application.get_response(