Description of problem:
on systems with glibc-2.2.93-5, you can connect to localhost by typing
'telnet 0 [port]'
on systems with glibc-2.3.2-4.80.6, typing telnet 0 returns
telnet: 0: Name or service not known
0: Unknown host

Version-Release number of selected component (if applicable):
8

How reproducible:
example, on a mail server, 'telnet 0 25' should connect to localhost:25

Steps to Reproduce:
1. telnet 0 25
2.
3.
  
Actual results:
telnet: 0: Name or service not known
0: Unknown host

Expected results:
Trying 0.0.0.0...
Connected to 0.
Escape character is '^]'.

Additional info:
This has only been seen on systems running glibc-2.3 or higher