[pitivi] Fix pylint dangerous-default-value

[Thibault Saunier <tsaunier src gnome org>]

commit ca702565b27f45df6a8660af33d9d8078043c9df
Author: Alexandru Băluț <alexandru balut gmail com>
Date:   Wed Oct 30 09:13:15 2019 +0100

    Fix pylint dangerous-default-value

 pitivi/preset.py            | 15 ++++++++-------
 pitivi/timeline/elements.py |  2 +-
 pitivi/utils/widgets.py     |  5 +++--
 pre-commit.hook             |  1 -
 4 files changed, 12 insertions(+), 11 deletions(-)
---
diff --git a/pitivi/preset.py b/pitivi/preset.py
index b75303c8..9a1e7cd1 100644
--- a/pitivi/preset.py
+++ b/pitivi/preset.py
@@ -176,7 +176,7 @@ class PresetManager(GObject.Object, Loggable):
             os.rename(self.user_path, "%s.old" % self.user_path)
         self._loadFromDir(self.user_path)
 
-    def _loadFromDir(self, presets_dir, extra={}):
+    def _loadFromDir(self, presets_dir, extra=None):
         try:
             files = os.listdir(presets_dir)
         except FileNotFoundError:
@@ -197,8 +197,9 @@ class PresetManager(GObject.Object, Loggable):
                     self.debug("Failed to load preset %s: %s", filepath, e)
                     continue
                 preset["filepath"] = filepath
-                for key, value in extra.items():
-                    preset[key] = value
+                if extra:
+                    for key, value in extra.items():
+                        preset[key] = value
                 self._addPreset(name, preset)
 
     def saveAll(self):
@@ -505,8 +506,8 @@ class EncodingTargetManager(PresetManager):
         self._removed_file_list = os.path.join(xdg_data_home(),
                                                'hidden_encoding_profiles.json')
         try:
-            with open(self._removed_file_list) as f:
-                self._removed_profiles = json.loads(f.read())
+            with open(self._removed_file_list) as removed:
+                self._removed_profiles = json.loads(removed.read())
         except FileNotFoundError:
             self._removed_profiles = []
 
@@ -587,8 +588,8 @@ class EncodingTargetManager(PresetManager):
         self.cur_preset = name
 
     def _save_removed_profiles(self):
-        with open(self._removed_file_list, 'w') as f:
-            json.dump(self._removed_profiles, f)
+        with open(self._removed_file_list, 'w') as removed:
+            json.dump(self._removed_profiles, removed)
 
     def removeCurrentPreset(self):
         self._removed_profiles.append(self.cur_preset)
diff --git a/pitivi/timeline/elements.py b/pitivi/timeline/elements.py
index 7a130229..95a2a4d9 100644
--- a/pitivi/timeline/elements.py
+++ b/pitivi/timeline/elements.py
@@ -721,7 +721,7 @@ class TimelineElement(Gtk.Layout, Zoomable, Loggable):
             res = source.set(inpoint + self._ges_elem.props.duration, val)
             assert res
 
-    def __create_keyframe_curve(self, bindings=[]):
+    def __create_keyframe_curve(self, bindings=None):
         """Creates required keyframe curve."""
         self.__removeKeyframes()
         if not bindings:
diff --git a/pitivi/utils/widgets.py b/pitivi/utils/widgets.py
index b174a5c9..22493df3 100644
--- a/pitivi/utils/widgets.py
+++ b/pitivi/utils/widgets.py
@@ -676,7 +676,7 @@ class GstElementSettingsWidget(Gtk.Box, Loggable):
         "x264enc": {"profile": Gst.ValueList(["high", "main", "baseline"])}
     }
 
-    def __init__(self, element, props_to_ignore=["name"], controllable=True):
+    def __init__(self, element, props_to_ignore=("name",), controllable=True):
         Gtk.Box.__init__(self)
         Loggable.__init__(self)
         self.element = element
@@ -811,7 +811,7 @@ class GstElementSettingsWidget(Gtk.Box, Loggable):
             grid.attach(label, 0, y, 1, 1)
             grid.attach(widget, 1, y, 1, 1)
 
-    def add_widgets(self, create_property_widget, values={}, with_reset_button=False, caps_values=None):
+    def add_widgets(self, create_property_widget, values=None, with_reset_button=False, caps_values=None):
         """Prepares a Gtk.Grid containing the property widgets of an element.
 
         Each property is on a separate row.
@@ -826,6 +826,7 @@ class GstElementSettingsWidget(Gtk.Box, Loggable):
             with_reset_button (bool): Whether to show a reset button for each
                 property.
         """
+        values = values or {}
         self.info("element: %s, use values: %s", self.element, values)
         self.properties.clear()
         self.__bindings_by_keyframe_button = {}
diff --git a/pre-commit.hook b/pre-commit.hook
index 78934e90..a1942d94 100755
--- a/pre-commit.hook
+++ b/pre-commit.hook
@@ -16,7 +16,6 @@ bin/pitivi.in
 pitivi/autoaligner.py
 pitivi/effects.py
 pitivi/medialibrary.py
-pitivi/preset.py
 pitivi/project.py
 pitivi/render.py
 pitivi/timeline/elements.py