Fix "TypeError: can only concatenate list (not tuple) to list" at `…

…cluster.py` line 946.

I should not merge PRs at the end of working day ...

elasticluster/cluster.py

@@ -943,8 +943,9 @@ def connect(self, keyfile=None):
                 log.debug("IP %s does not seem to belong to %s anymore. Ignoring!", self.preferred_ip, self.name)
                 self.preferred_ip = ips[0]
 
-        for ip in [self.preferred_ip] + ips:
-            if not ip: continue
+        for ip in itertools.chain([self.preferred_ip], ips):
+            if not ip:
+                continue
             try:
                 log.debug("Trying to connect to host %s (%s)",
                           self.name, ip)