Sync to trunk.

src/calibre/gui2/dialogs/metadata_single.py

@@ -951,8 +951,8 @@ class MetadataSingleDialog(ResizableDialog, Ui_MetadataSingleDialog):
             for w in getattr(self, 'custom_column_widgets', []):
                 self.books_to_refresh |= w.commit(self.id)
             self.db.commit()
-        except IOError, err:
+        except (IOError, OSError) as err:
-            if err.errno == 13: # Permission denied
+            if getattr(err, 'errno', -1) == 13: # Permission denied
                 fname = err.filename if err.filename else 'file'
                 return error_dialog(self, _('Permission denied'),
                         _('Could not open %s. Is it being used by another'

src/calibre/gui2/library/models.py

@@ -791,6 +791,16 @@ class BooksModel(QAbstractTableModel): # {{{
                 val = qt_to_dt(val, as_utc=False)
         elif typ == 'series':
             val = unicode(value.toString()).strip()
+            if val:
+                pat = re.compile(r'\[([.0-9]+)\]')
+                match = pat.search(val)
+                if match is not None:
+                    s_index = float(match.group(1))
+                    val = pat.sub('', val).strip()
+                elif val:
+                    if tweaks['series_index_auto_increment'] != 'const':
+                        s_index = self.db.get_next_cc_series_num_for(val,
+                                                        label=label, num=None)
         elif typ == 'composite':
             tmpl = unicode(value.toString()).strip()
             disp = cc['display']

src/calibre/library/custom_columns.py

@@ -484,7 +484,9 @@ class CustomColumns(object):
             if not existing:
                 existing = []
             for x in set(set_val) - set(existing):
-                if x is None:
+                # normalized types are text and ratings, so we can do this check
+                # to see if we need to re-add the value
+                if not x:
                     continue
                 case_change = False
                 existing = list(self.all_custom(num=data['num']))