tests: fix shutdown race in test-bad-pull

tests/test-bad-pull.t

@@ -13,12 +13,18 b''
   >         handler_class=SimpleHTTPServer.SimpleHTTPRequestHandler):
   >     server_address = ('localhost', int(os.environ['HGPORT']))
   >     httpd = server_class(server_address, handler_class)
-  >     os.system("hg clone http://localhost:$HGPORT/foo copy2&")
+  >     open("listening", "w")
   >     httpd.handle_request()
   > run()
   > EOF
 
-  $ python dumb.py
+  $ python dumb.py 2> log &
+  $ P=$!
+  $ while [ ! -f listening ]; do true; done
+  $ hg clone http://localhost:$HGPORT/foo copy2
+  abort: HTTP Error 404: * (glob)
+  [255]
+  $ wait $P
+  $ cat log
   localhost - - [*] code 404, message File not found (glob)
   localhost - - [*] "GET /foo?cmd=capabilities HTTP/1.1" 404 - (glob)
-  abort: HTTP Error 404: * (glob)