hg-ssh: parenthesize non-translated message

This is fixing for 'missing _() in ui message (use () to hide
false-positives)' check-code rule.

check-code has overlooked this, because a file isn't recognized as one
to be checked (this problem is fixed by subsequent patch).

contrib/hg-ssh

@@ -77,7 +77,7 b' def main():'
         sys.exit(255)
 
 def rejectpush(ui, **kwargs):
-    ui.warn("Permission denied\n")
+    ui.warn(("Permission denied\n"))
     # mercurial hooks use unix process conventions for hook return values
     # so a truthy return means failure
     return True