Allow to ignore plugin conflicts via environment

src/pretix/base/plugins.py

@@ -1,3 +1,4 @@
+import os
 import sys
 from enum import Enum
 from typing import List
@@ -51,7 +52,7 @@ class PluginConfig(AppConfig):
         if not hasattr(self, 'PretixPluginMeta'):
             raise ImproperlyConfigured("A pretix plugin config should have a PretixPluginMeta inner class.")
 
-        if hasattr(self.PretixPluginMeta, 'compatibility') and not self.IGNORE:
+        if hasattr(self.PretixPluginMeta, 'compatibility') and not os.environ.get("PRETIX_IGNORE_CONFLICTS") == "True":
             import pkg_resources
             try:
                 pkg_resources.require(self.PretixPluginMeta.compatibility)

src/setup.py

@@ -42,15 +42,14 @@ except:
 class CustomBuild(build):
     def run(self):
         os.environ.setdefault("DJANGO_SETTINGS_MODULE", "pretix.settings")
+        os.environ.setdefault("PRETIX_IGNORE_CONFLICTS", "True")
         import django
         django.setup()
         from django.conf import settings
         from django.core import management
-        from pretix.base.plugins import PluginConfig
 
         settings.COMPRESS_ENABLED = True
         settings.COMPRESS_OFFLINE = True
-        PluginConfig.IGNORE = True
 
         management.call_command('compilemessages', verbosity=1)
         management.call_command('compilejsi18n', verbosity=1)