diff -r 6386f9a421d2 -r d121823072b8 mercurial/debugcommands.py
--- a/mercurial/debugcommands.py	Thu Mar 14 09:12:55 2019 +0000
+++ b/mercurial/debugcommands.py	Fri Mar 15 15:07:43 2019 +0000
@@ -1476,13 +1476,13 @@
             raise error.Abort(msg)
 
     if opts.get(r'clear'):
-        with repo.lock():
+        with repo.wlock():
             cache = getcache()
             cache.clear(clear_persisted_data=True)
             return
 
     if add:
-        with repo.lock():
+        with repo.wlock():
             m = repo.manifestlog
             store = m.getstorage(b'')
             for n in add: