Fix context managers behavior on exceptions.

qutebrowser/utils/debug.py

@@ -230,10 +230,12 @@ def log_time(logger, action='operation'):
         action: A description of what's being done.
     """
     started = datetime.datetime.now()
-    yield
-    finished = datetime.datetime.now()
-    delta = (finished - started).total_seconds()
-    logger.debug("{} took {} seconds.".format(action.capitalize(), delta))
+    try:
+        yield
+    finally:
+        finished = datetime.datetime.now()
+        delta = (finished - started).total_seconds()
+        logger.debug("{} took {} seconds.".format(action.capitalize(), delta))
 
 
 def _get_widgets():

qutebrowser/utils/log.py

@@ -159,8 +159,10 @@ def init_log(args):
 def disable_qt_msghandler():
     """Contextmanager which temporarily disables the Qt message handler."""
     old_handler = QtCore.qInstallMessageHandler(None)
-    yield
-    QtCore.qInstallMessageHandler(old_handler)
+    try:
+        yield
+    finally:
+        QtCore.qInstallMessageHandler(old_handler)
 
 
 def _init_handlers(level, color, ram_capacity):
@@ -319,8 +321,10 @@ def hide_qt_warning(pattern, logger='qt'):
     log_filter = QtWarningFilter(pattern)
     logger_obj = logging.getLogger(logger)
     logger_obj.addFilter(log_filter)
-    yield
-    logger_obj.removeFilter(log_filter)
+    try:
+        yield
+    finally:
+        logger_obj.removeFilter(log_filter)
 
 
 class QtWarningFilter(logging.Filter):

qutebrowser/utils/utils.py

@@ -438,11 +438,13 @@ def disabled_excepthook():
     """Run code with the exception hook temporarily disabled."""
     old_excepthook = sys.excepthook
     sys.excepthook = sys.__excepthook__
-    yield
-    # If the code we did run did change sys.excepthook, we leave it
-    # unchanged. Otherwise, we reset it.
-    if sys.excepthook is sys.__excepthook__:
-        sys.excepthook = old_excepthook
+    try:
+        yield
+    finally:
+        # If the code we did run did change sys.excepthook, we leave it
+        # unchanged. Otherwise, we reset it.
+        if sys.excepthook is sys.__excepthook__:
+            sys.excepthook = old_excepthook
 
 
 class prevent_exceptions:  # pylint: disable=invalid-name