Added compatibility with python 3.7 (celery#4902)

celery/app/routes.py

@@ -17,6 +17,12 @@
 from celery.utils.functional import maybe_evaluate, mlazy
 from celery.utils.imports import symbol_by_name
 
+try:
+    Pattern = re._pattern_type
+except AttributeError:  # pragma: no cover
+    # for support Python 3.7
+    Pattern = re.Pattern
+
 __all__ = ('MapRoute', 'Router', 'prepare')
 
 
@@ -33,7 +39,7 @@ def __init__(self, map):
         self.map = {}
         self.patterns = OrderedDict()
         for k, v in map:
-            if isinstance(k, re._pattern_type):
+            if isinstance(k, Pattern):
                 self.patterns[k] = v
             elif '*' in k:
                 self.patterns[re.compile(glob_to_re(k))] = v

t/unit/app/test_routes.py

@@ -78,12 +78,17 @@ def test_route_for_task(self):
         assert route('celery.awesome') is None
 
     def test_route_for_task__glob(self):
+        from re import compile
+
         route = routes.MapRoute([
             ('proj.tasks.*', 'routeA'),
             ('demoapp.tasks.bar.*', {'exchange': 'routeB'}),
+            (compile(r'(video|image)\.tasks\..*'), {'queue': 'media'}),
         ])
         assert route('proj.tasks.foo') == {'queue': 'routeA'}
         assert route('demoapp.tasks.bar.moo') == {'exchange': 'routeB'}
+        assert route('video.tasks.foo') == {'queue': 'media'}
+        assert route('image.tasks.foo') == {'queue': 'media'}
         assert route('demoapp.foo.bar.moo') is None
 
     def test_expand_route_not_found(self):