diff -r 4f40dc190f63 -r 612b4b63fb22 hgext/remotefilelog/shallowrepo.py
--- a/hgext/remotefilelog/shallowrepo.py	Mon Dec 09 11:26:53 2019 +0100
+++ b/hgext/remotefilelog/shallowrepo.py	Mon Dec 09 12:29:46 2019 +0100
@@ -215,13 +215,7 @@
             )
 
         def backgroundprefetch(
-            self,
-            revs,
-            base=None,
-            repack=False,
-            pats=None,
-            opts=None,
-            ensurestart=False,
+            self, revs, base=None, repack=False, pats=None, opts=None
         ):
             """Runs prefetch in background with optional repack
             """
@@ -237,7 +231,7 @@
                 kwargs['record_wait'] = repo.ui.atexit
 
             procutil.runbgcommand(
-                cmd, encoding.environ, ensurestart=ensurestart, **kwargs
+                cmd, encoding.environ, ensurestart=False, **kwargs
             )
 
         def prefetch(self, revs, base=None, pats=None, opts=None):