diff --git a/mercurial/revlog.py b/mercurial/revlog.py
--- a/mercurial/revlog.py
+++ b/mercurial/revlog.py
@@ -34,7 +34,9 @@ REVLOG_DEFAULT_VERSION = REVLOG_DEFAULT_
 REVLOGNG_FLAGS = REVLOGNGINLINEDATA | REVLOGGENERALDELTA
 
 # revlog index flags
-REVIDX_KNOWN_FLAGS = 0
+REVIDX_ISCENSORED = (1 << 15) # revision has censor metadata, must be verified
+REVIDX_DEFAULT_FLAGS = 0
+REVIDX_KNOWN_FLAGS = REVIDX_ISCENSORED
 
 # max size of revlog with inline data
 _maxinline = 131072