diff -r 1df7e7b8558e -r 04c319a07c7b mercurial/url.py
--- a/mercurial/url.py	Sun Feb 25 22:30:14 2018 -0500
+++ b/mercurial/url.py	Sun Feb 25 23:08:41 2018 -0500
@@ -449,7 +449,7 @@
             self.cookiejar = cookiejar
         except util.cookielib.LoadError as e:
             ui.warn(_('(error loading cookie file %s: %s; continuing without '
-                      'cookies)\n') % (cookiefile, str(e)))
+                      'cookies)\n') % (cookiefile, util.forcebytestr(e)))
 
     def http_request(self, request):
         if self.cookiejar: