diff -r 346af7687c6f -r 89a2afe31e82 mercurial/utils/cborutil.py
--- a/mercurial/utils/cborutil.py	Fri Nov 27 17:00:00 2020 -0500
+++ b/mercurial/utils/cborutil.py	Fri Nov 27 17:03:29 2020 -0500
@@ -641,19 +641,28 @@
 
                 elif special == SPECIAL_START_ARRAY:
                     self._collectionstack.append(
-                        {b'remaining': value, b'v': [],}
+                        {
+                            b'remaining': value,
+                            b'v': [],
+                        }
                     )
                     self._state = self._STATE_WANT_ARRAY_VALUE
 
                 elif special == SPECIAL_START_MAP:
                     self._collectionstack.append(
-                        {b'remaining': value, b'v': {},}
+                        {
+                            b'remaining': value,
+                            b'v': {},
+                        }
                     )
                     self._state = self._STATE_WANT_MAP_KEY
 
                 elif special == SPECIAL_START_SET:
                     self._collectionstack.append(
-                        {b'remaining': value, b'v': set(),}
+                        {
+                            b'remaining': value,
+                            b'v': set(),
+                        }
                     )
                     self._state = self._STATE_WANT_SET_VALUE
 
@@ -684,7 +693,10 @@
                     lastc[b'remaining'] -= 1
 
                     self._collectionstack.append(
-                        {b'remaining': value, b'v': newvalue,}
+                        {
+                            b'remaining': value,
+                            b'v': newvalue,
+                        }
                     )
 
                     # self._state doesn't need changed.
@@ -711,7 +723,10 @@
                     lastc[b'remaining'] -= 1
 
                     self._collectionstack.append(
-                        {b'remaining': value, b'v': newvalue,}
+                        {
+                            b'remaining': value,
+                            b'v': newvalue,
+                        }
                     )
 
                     self._state = self._STATE_WANT_SET_VALUE
@@ -775,7 +790,10 @@
                     lastc[b'remaining'] -= 1
 
                     self._collectionstack.append(
-                        {b'remaining': value, b'v': newvalue,}
+                        {
+                            b'remaining': value,
+                            b'v': newvalue,
+                        }
                     )
 
                     self._state = self._STATE_WANT_ARRAY_VALUE
@@ -789,7 +807,10 @@
                     lastc[b'remaining'] -= 1
 
                     self._collectionstack.append(
-                        {b'remaining': value, b'v': newvalue,}
+                        {
+                            b'remaining': value,
+                            b'v': newvalue,
+                        }
                     )
 
                     self._state = self._STATE_WANT_MAP_KEY
@@ -803,7 +824,10 @@
                     lastc[b'remaining'] -= 1
 
                     self._collectionstack.append(
-                        {b'remaining': value, b'v': newvalue,}
+                        {
+                            b'remaining': value,
+                            b'v': newvalue,
+                        }
                     )
 
                     self._state = self._STATE_WANT_SET_VALUE