Merge from trunk

resources/default_tweaks.py

@@ -143,7 +143,7 @@ auto_connect_to_folder = ''
 # documentation, 'Darkover' is called the value and 'My Series' is called the
 # category. If two books have fields that generate the same collection name,
 # then both books will be in that collection.
-# This set of tweaks tweak lets you specify for a standard or custom field how
+# This set of tweaks lets you specify for a standard or custom field how
 # the collections are to be named. You can use it to add a description to a
 # standard field, for example 'Foo (Tag)' instead of the 'Foo'. You can also use
 # it to force multiple fields to end up in the same collection. For example, you

src/calibre/ebooks/mobi/mobiml.py

@@ -468,8 +468,9 @@ class MobiMLizer(object):
                         vtag.append(child)
                     else:
                         break
-                for child in vbstate.para:
-                    vtag.append(child)
+                if vbstate.para is not None:
+                    for child in vbstate.para:
+                        vtag.append(child)
                 return
 
         if text or tag in CONTENT_TAGS or tag in NESTABLE_TAGS: