zeroconf: notify the Zeroconf threads when hg exits

Zeroconf launches two threads in the background, and they wait on
Condition objects to exit. We need to call Zeroconf.close() to
release those conditions so that threads can gracefully exit.

This means that an interrupt on the hg process will now gracefully
propagate to the Zeroconf children, fixing that bug which did not
allow us to kill an `hg serve` process.

hgext/zeroconf/__init__.py

@@ -27,7 +27,7 b' You can discover Zeroconf-enabled reposi'
 import socket, time, os
 
 import Zeroconf
-from mercurial import ui, hg, encoding, util
+from mercurial import ui, hg, encoding, util, dispatch
 from mercurial import extensions
 from mercurial.hgweb import hgweb_mod
 from mercurial.hgweb import hgwebdir_mod
@@ -166,6 +166,18 b' def defaultdest(orig, source):'
             return name.encode(encoding.encoding)
     return orig(source)
 
+def cleanupafterdispatch(orig, ui, options, cmd, cmdfunc):
+    try:
+        return orig(ui, options, cmd, cmdfunc)
+    finally:
+        # we need to call close() on the server to notify() the various
+        # threading Conditions and allow the background threads to exit
+        global server
+        if server:
+            server.close()
+
+extensions.wrapfunction(dispatch, '_runcommand', cleanupafterdispatch)
+
 extensions.wrapfunction(ui.ui, 'config', config)
 extensions.wrapfunction(ui.ui, 'configitems', configitems)
 extensions.wrapfunction(hg, 'defaultdest', defaultdest)