Improve logging for BaseKeyParser

See #1653

qutebrowser/keyinput/basekeyparser.py

@@ -129,7 +129,7 @@ class BaseKeyParser(QObject):
         try:
             cmdstr = self.special_bindings[binding]
         except KeyError:
-            self._debug_log("No binding found for {}.".format(binding))
+            self._debug_log("No special binding found for {}.".format(binding))
             return False
         self.execute(cmdstr, self.Type.special)
         return True

tests/end2end/features/keyinput.feature

@@ -80,7 +80,7 @@ Feature: Keyboard input
     Scenario: Unbinding a built-in binding
         When I run :unbind o
         And I press the key "o"
-        Then "No binding found for o." should be logged
+        Then "Giving up with 'o', no matches" should be logged
         # maybe check it's unbound in the config?
 
     Scenario: Binding and unbinding a special keychain with differing case (issue 1544)