Some simple changes from code review.

testtools/_spinner.py

@@ -194,7 +194,12 @@ class Spinner(object):
         self._stop_reactor()
 
     def _clean(self):
-        """Clean up any junk in the reactor."""
+        """Clean up any junk in the reactor.
+
+        This will *always* spin the reactor at least once.  We do this in
+        order to give the reactor a chance to do the disconnections and
+        terminations that were asked of it.
+        """
         # If we've just run a method that calls, say, loseConnection and then
         # returns, then the reactor might not have had a chance to actually
         # close the connection yet.  Here we explicitly give it such a chance.

testtools/deferredruntest.py

@@ -240,11 +240,8 @@ class AsynchronousDeferredRunTest(RunTest):
         if successful:
             self.result.addSuccess(self.case, details=self.case.getDetails())
         else:
-            # XXX: Maybe we should only add this when there is something worth
-            # adding? i.e. don't add when it's empty.
             self.case.addDetail(
-                'twisted-log',
-                Content(UTF8_TEXT, lambda: [full_log.getvalue()]))
+                'twisted-log', Content(UTF8_TEXT, full_log.readlines))
 
     def _run_user(self, function, *args):
         """Run a user-supplied function.