Fix adding of URLs to history completion.

Before, the item_added signal was emitted *after* an item was added, which
means the on_history_item_added slot always assumed the item already is in the
history.

qutebrowser/browser/history.py

@@ -65,8 +65,15 @@ class WebHistory(QWebHistoryInterface):
         _history_dict: An OrderedDict of URLs read from the on-disk history.
         _new_history: A list of HistoryEntry items of the current session.
         _saved_count: How many HistoryEntries have been written to disk.
+
+    Signals:
+        item_about_to_be_added: Emitted before a new HistoryEntry is added.
+                                arg: The new HistoryEntry.
+        item_added: Emitted after a new HistoryEntry is added.
+                    arg: The new HistoryEntry.
     """
 
+    item_about_to_be_added = pyqtSignal(HistoryEntry)
     item_added = pyqtSignal(HistoryEntry)
 
     def __init__(self, parent=None):
@@ -120,6 +127,7 @@ class WebHistory(QWebHistoryInterface):
         """
         if not config.get('general', 'private-browsing'):
             entry = HistoryEntry(time.time(), url_string)
+            self.item_about_to_be_added.emit(entry)
             self._new_history.append(entry)
             self._history_dict[url_string] = entry
             self._history_dict.move_to_end(url_string)

qutebrowser/completion/models/urlmodel.py

@@ -55,7 +55,8 @@ class UrlCompletionModel(base.BaseCompletionModel):
             self.new_item(self._history_cat, entry.url, "",
                           self._fmt_atime(entry.atime), sort=int(entry.atime))
 
-        self._history.item_added.connect(self.on_history_item_added)
+        self._history.item_about_to_be_added.connect(
+            self.on_history_item_added)
         objreg.get('config').changed.connect(self.reformat_timestamps)
 
     def _fmt_atime(self, atime):