diff -r 05c80f9ef100 -r 92ac6b1697a7 mercurial/revlogutils/constants.py
--- a/mercurial/revlogutils/constants.py	Thu Aug 08 01:04:48 2019 +0200
+++ b/mercurial/revlogutils/constants.py	Thu Aug 08 01:28:34 2019 +0200
@@ -11,7 +11,6 @@
 
 from .. import (
     repository,
-    util,
 )
 
 # revlog header flags
@@ -48,7 +47,7 @@
     REVIDX_ELLIPSIS,
     REVIDX_EXTSTORED,
 ]
-REVIDX_KNOWN_FLAGS = util.bitsfrom(REVIDX_FLAGS_ORDER)
+
 # bitmark for flags that could cause rawdata content change
 REVIDX_RAWTEXT_CHANGING_FLAGS = REVIDX_ISCENSORED | REVIDX_EXTSTORED