Resolve KeyError when deleting URL with space.

Resolves #2963.

qutebrowser/browser/history.py

@@ -26,7 +26,7 @@ from PyQt5.QtCore import pyqtSlot, QUrl, QTimer
 
 from qutebrowser.commands import cmdutils, cmdexc
 from qutebrowser.utils import (utils, objreg, log, usertypes, message,
-                               debug, standarddir)
+                               debug, standarddir, qtutils)
 from qutebrowser.misc import objects, sql
 
 
@@ -144,8 +144,10 @@ class WebHistory(sql.SqlTable):
         Args:
             url: URL string to delete.
         """
-        self.delete('url', url)
+        qurl = QUrl(url)
-        self.completion.delete('url', url)
+        qtutils.ensure_valid(qurl)
+        self.delete('url', self._format_url(qurl))
+        self.completion.delete('url', self._format_completion_url(qurl))
 
     @pyqtSlot(QUrl, QUrl, str)
     def add_from_tab(self, url, requested_url, title):

tests/unit/browser/test_history.py

@@ -127,21 +127,25 @@ def test_clear_force(qtbot, tmpdir, hist):
     assert not len(hist.completion)
 
 
-def test_delete_url(hist):
+@pytest.mark.parametrize('raw, escaped', [
+    ('http://example.com/1', 'http://example.com/1'),
+    ('http://example.com/1 2', 'http://example.com/1%202'),
+])
+def test_delete_url(hist, raw, escaped):
     hist.add_url(QUrl('http://example.com/'), atime=0)
-    hist.add_url(QUrl('http://example.com/1'), atime=0)
+    hist.add_url(QUrl(escaped), atime=0)
     hist.add_url(QUrl('http://example.com/2'), atime=0)
 
     before = set(hist)
     completion_before = set(hist.completion)
 
-    hist.delete_url(QUrl('http://example.com/1'))
+    hist.delete_url(QUrl(raw))
 
     diff = before.difference(set(hist))
-    assert diff == {('http://example.com/1', '', 0, False)}
+    assert diff == {(escaped, '', 0, False)}
 
     completion_diff = completion_before.difference(set(hist.completion))
-    assert completion_diff == {('http://example.com/1', '', 0)}
+    assert completion_diff == {(raw, '', 0)}
 
 
 @pytest.mark.parametrize(