Do not include locally installed plugins in test settings

src/pretix/settings.py

@@ -187,7 +187,9 @@ try:
 except ImportError:
     pass
 
+PLUGINS = []
 for entry_point in iter_entry_points(group='pretix.plugin', name=None):
+    PLUGINS.append(entry_point.module_name)
     INSTALLED_APPS.append(entry_point.module_name)
 
 CORE_MODULES = {

src/tests/settings.py

@@ -7,3 +7,6 @@ TEST_DIR = os.path.dirname(__file__)
 TEMPLATES[0]['DIRS'].append(os.path.join(TEST_DIR, 'templates'))  # NOQA
 
 INSTALLED_APPS.append('tests.testdummy')  # NOQA
+
+for a in PLUGINS:
+    INSTALLED_APPS.remove(a)