Stabilize history tests

Get current URL right away in :view-source, and wait until source is shown in
the test.

qutebrowser/browser/commands.py

@@ -1450,14 +1450,14 @@ class CommandDispatcher:
         if tab.data.viewing_source:
             raise cmdexc.CommandError("Already viewing source!")
 
+        try:
+            current_url = self._current_url()
+        except cmdexc.CommandError as e:
+            message.error(str(e))
+            return
+
         def show_source_cb(source):
             """Show source as soon as it's ready."""
-            try:
-                current_url = self._current_url()
-            except cmdexc.CommandError as e:
-                message.error(str(e))
-                return
-
             lexer = pygments.lexers.HtmlLexer()
             formatter = pygments.formatters.HtmlFormatter(
                 full=True, linenos='table',

tests/end2end/features/history.feature

@@ -67,6 +67,7 @@ Feature: Page history
     Scenario: History with view-source URL
         When I open data/title.html
         And I run :view-source
+        And I wait for "Changing title for idx * to 'Source for http://localhost:*/data/title.html'" in the log
         Then the history file should contain:
             http://localhost:(port)/data/title.html Test title