exchange: print full reason variable

This commit essentially reverts 69ac9aebbc55.

urllib2.URLError receives a "reason" argument. It isn't always a
tuple. Mozilla has experienced at least IndexError failures due
to the reason[1] access.
https://bugzilla.mozilla.org/show_bug.cgi?id=1364687

mercurial/exchange.py

@@ -2018,7 +2018,7 b' def trypullbundlefromurl(ui, repo, url):'
             except urlerr.httperror as e:
                 ui.warn(_('HTTP error fetching bundle: %s\n') % str(e))
             except urlerr.urlerror as e:
-                ui.warn(_('error fetching bundle: %s\n') % e.reason[1])
+                ui.warn(_('error fetching bundle: %s\n') % e.reason)
 
             return False
         finally: