mercurial/configitems.py

--- a/mercurial/configitems.py	Wed Apr 07 13:31:15 2021 +0200
+++ b/mercurial/configitems.py	Tue Apr 06 18:55:19 2021 +0200
@@ -1307,7 +1307,7 @@
 coreconfigitem(
     b'format',
     b'revlog-compression',
-    default=lambda: [b'zlib'],
+    default=lambda: [b'zstd', b'zlib'],
     alias=[(b'experimental', b'format.compression')],
 )
 coreconfigitem(