async_connect fails under WebServer 2.4

Imported from http://bugzilla.roxen.com/bugzilla/show_bug.cgi?id=2691

Reported by Martin Nilsson, IDA nilsson@pike.ida.liu.se

The debug log gets filled with a lot of these:

DNS: Failed to read UDP packet. Connection refused?
Stdio.File(): not open.
module.File: Stdio.File(0, 0, 777 /* fd=-1 */)->query_address()
/export/d1/nilsson/pike/7.3.13/lib/modules/Stdio.pmod/module.pmod (version
1.133):368: Stdio.File(0, 0, 777 /* fd=-1
*/)->async_connect("194.52.182.15",80,Query()->__lambda_65930_0_line_250)
/export/d1/nilsson/pike/7.3.13/lib/modules/Protocols.pmod/HTTP.pmod/Query.pike
(version 1.39):280: Query()->async_got_host("194.52.182.15",80)
/export/d1/nilsson/pike/7.3.13/lib/modules/Protocols.pmod/HTTP.pmod/Query.pike
(version 1.39):337:
Query()->dns_lookup_callback("www.roxen.com","194.52.182.15",Query()->async_got_host,80)
/export/d1/nilsson/pike/7.3.13/lib/modules/Protocols.pmod/DNS.pmod (version
1.61):917:
Stdio.UDP()->generic_get("www.roxen.com",mapping[21],-1,0,1,"a","www.roxen.com",Query()->dns_lookup_callback,Query()->async_got_host,80)
/export/d1/nilsson/pike/7.3.13/lib/modules/Protocols.pmod/DNS.pmod (version
1.61):880: Stdio.UDP()->rec_data(mapping[3])
/export/d1/nilsson/pike/7.3.13/lib/modules/Stdio.pmod/module.pmod (version
1.133):2340: Stdio.UDP()->_read_callback()
Unknown program: `()(3600.000000)