patchbomb: python 3 really wants those email addresses in unicode

At this point, test-patchbomb-tls.t almost passes on Python 3, but I'm
not really sure what the issue is: we just get a `abort: Connection
unexpectedly closed` that doesn't make sense to me.

Differential Revision: https://phab.mercurial-scm.org/D3957

hgext/patchbomb.py

@@ -818,6 +818,8 b' def email(ui, repo, *revs, **opts):'
             generator = emailgen.Generator(_bytesgenerator(fp),
                                            mangle_from_=False)
             generator.flatten(m, 0)
-            sendmail(sender_addr, to + bcc + cc, fp.getvalue())
+            alldests = to + bcc + cc
+            alldests = [encoding.strfromlocal(d) for d in alldests]
+            sendmail(sender_addr, alldests, fp.getvalue())
 
     progress.complete()