--- a/mercurial/util.py	Thu Mar 26 10:09:17 2020 -0400
+++ b/mercurial/util.py	Tue Mar 31 15:11:33 2020 +0530
@@ -130,6 +130,16 @@
 unlink = platform.unlink
 username = platform.username
 
+
+def setumask(val):
+    ''' updates the umask. used by chg server '''
+    if pycompat.iswindows:
+        return
+    os.umask(val)
+    global umask
+    platform.umask = umask = val & 0o777
+
+
 # small compat layer
 compengines = compression.compengines
 SERVERROLE = compression.SERVERROLE