Page title is lost at navigation

[arza-zara]

When the title should stay the same in navigation, in some cases it's replaced with the URL.

To reproduce:

• Open a page that has a title.
• Press g o enter.

→ The title is replaced with the URL.

Or:

• Open a GitHub PR page.
• Click "Files changed" tab.
• Press H.

→ The title is replaced with the URL.

commands  command:run:541 command called: back
commands  command:run:555 Calling qutebrowser.browser.commands.CommandDispatcher.back(<qutebrowser.browser.commands.CommandDispatcher>, False, False, False, 1)
webview   browsertab:_on_before_load_started:961 Going to start loading: https://github.com/qutebrowser/qutebrowser/pull/5209
webview   tabbedbrowser:_on_title_changed:750 Changing title for idx 3 to 'https://github.com/qutebrowser/qutebrowser/pull/5209'
webview   browsertab:_on_before_load_started:961 Going to start loading: https://github.com/qutebrowser/qutebrowser/pull/5209
webview   tabbedbrowser:_on_title_changed:750 Changing title for idx 3 to 'https://github.com/qutebrowser/qutebrowser/pull/5209'
modes     modeman:_handle_keypress:268 match: 2, forward_unbound_keys: auto, passthrough: True, is_non_alnum: True, dry_run: False --> filter: True (focused: <PyQt5.QtWidgets.QWidget object at 0x7fc0b0967160>)
webview   browsertab:_set_load_status:927 load status for <qutebrowser.browser.webengine.webenginetab.WebEngineTab tab_id=3 url='https://github.com/qutebrowser/qutebrowser/pull/5209/files'>: LoadStatus.success_https
signals   signalfilter:_filter_signals:87 emitting: cur_load_status_changed(<LoadStatus.success_https: 3>) (tab 3)
webview   browsertab:_set_load_status:927 load status for <qutebrowser.browser.webengine.webenginetab.WebEngineTab tab_id=3 url='https://github.com/qutebrowser/qutebrowser/pull/5209/files'>: LoadStatus.loading
signals   signalfilter:_filter_signals:87 emitting: cur_load_status_changed(<LoadStatus.loading: 6>) (tab 3)
signals   signalfilter:_filter_signals:87 emitting: cur_load_started() (tab 3)
modes     modeman:_handle_keyrelease:293 filter: True
signals   signalfilter:_filter_signals:87 emitting: cur_url_changed(PyQt5.QtCore.QUrl('https://github.com/qutebrowser/qutebrowser/pull/5209')) (tab 3)
webview   browsertab:_set_load_status:927 load status for <qutebrowser.browser.webengine.webenginetab.WebEngineTab tab_id=3 url='https://github.com/qutebrowser/qutebrowser/pull/5209'>: LoadStatus.success_https
signals   signalfilter:_filter_signals:87 emitting: cur_load_status_changed(<LoadStatus.success_https: 3>) (tab 3)

I tried setting the title in _on_load_finished (arza-zara@c23936a) – this fixes only the former case.

--- qutebrowser/browser/browsertab.py
+++ qutebrowser/browser/browsertab.py
@@ -1020,5 +1020,7 @@ class AbstractTab(QWidget):
         self.load_finished.emit(ok)
 
-        if not self.title():
+        if self.title():
+            self.title_changed.emit(self.title())
+        else:
             self.title_changed.emit(self.url().toDisplayString())

df45e74, Qt 5.14.1, Chromium 77.0.3865.129

[The-Compiler]

Another case of this happening as outlined on Reddit:

• Title disappears after following a page hash change or a PHP POST request : qutebrowser
• When I go back after sending a POST form to the same page, the title disappears. : qutebrowser

Log:
qutebrowser.log

Screecast:

qutebrowser.mp4

[arza-zara]

Workaround: :bind st jseval document.title=document.title+'.'