exchange: fix an attempt to format a list into bytes

This goes with 27c6d6f53d46.

Differential Revision: https://phab.mercurial-scm.org/D7583

mercurial/exchange.py

@@ -2202,7 +2202,7 b' def applynarrowacl(repo, kwargs):'
     if invalid_includes:
         raise error.Abort(
             _(b"The following includes are not accessible for %s: %s")
-            % (username, invalid_includes)
+            % (username, stringutil.pprint(invalid_includes))
         )
 
     new_args = {}