diff -r 08e26ef4ad35 -r 119790e1c67c mercurial/revlogutils/flagutil.py
--- a/mercurial/revlogutils/flagutil.py	Thu Apr 08 16:34:11 2021 +0200
+++ b/mercurial/revlogutils/flagutil.py	Sat Apr 10 11:27:40 2021 +0200
@@ -18,7 +18,6 @@
     REVIDX_HASCOPIESINFO,
     REVIDX_ISCENSORED,
     REVIDX_RAWTEXT_CHANGING_FLAGS,
-    REVIDX_SIDEDATA,
 )
 
 from .. import error, util
@@ -28,7 +27,6 @@
 REVIDX_ISCENSORED
 REVIDX_ELLIPSIS
 REVIDX_EXTSTORED
-REVIDX_SIDEDATA
 REVIDX_HASCOPIESINFO,
 REVIDX_DEFAULT_FLAGS
 REVIDX_FLAGS_ORDER