zeroconf: fix non existant formatting in the vendored zeroconf module

On Tue Mar 1st 2016 at 09:33:39 timeless decided to wrap long line in
`hgext/zeroconf/Zeroconf.py`. Doing so, he fat fingered a "%w" instead of a "%s"
in a string. %w does not exists, 4 year later, pyflakes (rightfully) complains
about it. So I am fixing it.

Differential Revision: https://phab.mercurial-scm.org/D8627

hgext/zeroconf/Zeroconf.py

@@ -1647,7 +1647,7 b' class Zeroconf(object):'
                     and record.alias == info.name
                 ):
                     if info.name.find(b'.') < 0:
-                        info.name = b"%w.[%s:%d].%s" % (
+                        info.name = b"%s.[%s:%d].%s" % (
                             info.name,
                             info.address,
                             info.port,