--- a/mercurial/revlogutils/constants.py Mon May 03 20:22:34 2021 +0200
+++ b/mercurial/revlogutils/constants.py Mon May 03 19:46:25 2021 +0200
@@ -119,6 +119,10 @@
# These constants are used in revlog version >=2 to denote the compression used
# for a chunk.
+# Chunk use no compression, the data stored on disk can be directly use as
+# chunk value. Without any header information prefixed.
+COMP_MODE_PLAIN = 0
+
# Chunk use a compression mode stored "inline" at the start of the chunk
# itself. This is the mode always used for revlog version "0" and "1"
COMP_MODE_INLINE = 2