[pygobject/pygobject-3-36] flake8: fix errors with new flake8 3.8.0

[Christoph Reiter <creiter src gnome org>]

commit 4500bec2894c534fa11190a45bd58c8f5de6dca9
Author: Christoph Reiter <reiter christoph gmail com>
Date:   Sun May 17 23:01:11 2020 +0200

    flake8: fix errors with new flake8 3.8.0

 examples/demo/demos/printing.py | 4 ++--
 tests/test_gobject.py           | 8 ++++----
 tests/test_gtk_template.py      | 4 ++++
 3 files changed, 10 insertions(+), 6 deletions(-)
---
diff --git a/examples/demo/demos/printing.py b/examples/demo/demos/printing.py
index 6e68037d..a87bd6fd 100644
--- a/examples/demo/demos/printing.py
+++ b/examples/demo/demos/printing.py
@@ -92,8 +92,8 @@ class PrintingApp:
         file_path = print_data['filename']
         if not os.path.isfile(file_path):
             file_path = os.path.join('demos', file_path)
-            if not os.path.isfile:
-                raise Exception("file not found: " % (file_path, ))
+            if not os.path.isfile(file_path):
+                raise Exception("file not found: %s" % (file_path, ))
 
         # in reality you should most likely not read the entire
         # file into a buffer
diff --git a/tests/test_gobject.py b/tests/test_gobject.py
index bba12cb7..1e557de7 100644
--- a/tests/test_gobject.py
+++ b/tests/test_gobject.py
@@ -804,8 +804,8 @@ class TestGValue(unittest.TestCase):
 
 def test_list_properties():
 
-    def find_param(l, name):
-        for param in l:
+    def find_param(props, name):
+        for param in props:
             if param.name == name:
                 return param
         return
@@ -822,8 +822,8 @@ def test_list_properties():
     props = list_props(Gio.SimpleAction)
     assert find_param(props, "enabled")
 
-    def names(l):
-        return [p.name for p in l]
+    def names(props):
+        return [p.name for p in props]
 
     assert (set(names(list_props(Gio.Action))) <=
             set(names(list_props(Gio.SimpleAction))))
diff --git a/tests/test_gtk_template.py b/tests/test_gtk_template.py
index db3c8d98..d6745495 100644
--- a/tests/test_gtk_template.py
+++ b/tests/test_gtk_template.py
@@ -599,6 +599,7 @@ def test_template_hierarchy():
       </template>
      </interface>
     """
+
     @Gtk.Template(string=testlabel)
     class TestLabel(Gtk.Label):
 
@@ -617,6 +618,7 @@ def test_template_hierarchy():
       </template>
     </interface>
     """
+
     @Gtk.Template(string=testbox)
     class TestBox(Gtk.Box):
 
@@ -643,6 +645,7 @@ def test_template_hierarchy():
       </template>
     </interface>
     """
+
     @Gtk.Template(string=window)
     class MyWindow(Gtk.Window):
 
@@ -672,6 +675,7 @@ def test_multiple_init_template_calls():
        </template>
      </interface>
     """
+
     @Gtk.Template(string=xml)
     class MyBox(Gtk.Box):