[439277] Fix Client constructor for the case where "localhost" is unresolvable.

Bug: https://bugs.eclipse.org/bugs/show_bug.cgi?id=439277
Change-Id: I05d268e4fbaba56116ea35bc8b2dc2c7f31ca2a9

ChangeLog.txt

@@ -2,6 +2,8 @@ v1.0.2
 ======
 
 - Fix "protocol" not being used in publish.single()
+- Fix Client constructor for the case where "localhost" is unresolvable.
+  Closes #439277.
 
 v1.0.1
 ======

src/paho/mqtt/client.py

@@ -252,7 +252,7 @@ def _socketpair_compat():
     """TCP/IP socketpair including Windows support"""
     listensock = socket.socket(socket.AF_INET, socket.SOCK_STREAM, socket.IPPROTO_IP)
     listensock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
-    listensock.bind(("localhost", 0))
+    listensock.bind(("127.0.0.1", 0))
     listensock.listen(1)
 
     iface, port = listensock.getsockname()