diff -r 3941fe53670d -r ee91966aec0f mercurial/wireprotov1server.py
--- a/mercurial/wireprotov1server.py	Thu Feb 18 15:07:45 2021 +0100
+++ b/mercurial/wireprotov1server.py	Wed Mar 03 14:00:45 2021 +0100
@@ -27,6 +27,7 @@
     exchange,
     pushkey as pushkeymod,
     pycompat,
+    requirements as requirementsmod,
     streamclone,
     util,
     wireprototypes,
@@ -310,7 +311,7 @@
             caps.append(b'stream-preferred')
         requiredformats = repo.requirements & repo.supportedformats
         # if our local revlogs are just revlogv1, add 'stream' cap
-        if not requiredformats - {b'revlogv1'}:
+        if not requiredformats - {requirementsmod.REVLOGV1_REQUIREMENT}:
             caps.append(b'stream')
         # otherwise, add 'streamreqs' detailing our local revlog format
         else: