forcibly disable roaming support in the client

ssh client security bug fix from
http://www.openssh.com/txt/release-7.1p2

openssh client is installed in gce instances.
although it's private key is not that much sensitive
it's better to land this security patch than not.

reported initially as cve-2016-0777 and cve-2016-0778
(January 14th, 2016)

BUG: 26587626
Change-Id: I113d576a3522ded8cb0f4a2e117999b0c51d4364
diff --git a/readconf.c b/readconf.c
index 42a2961..ebbf219 100644
--- a/readconf.c
+++ b/readconf.c
@@ -1660,7 +1660,7 @@
 	options->tun_remote = -1;
 	options->local_command = NULL;
 	options->permit_local_command = -1;
-	options->use_roaming = -1;
+	options->use_roaming = 0;
 	options->visual_host_key = -1;
 	options->ip_qos_interactive = -1;
 	options->ip_qos_bulk = -1;
@@ -1835,8 +1835,7 @@
 		options->tun_remote = SSH_TUNID_ANY;
 	if (options->permit_local_command == -1)
 		options->permit_local_command = 0;
-	if (options->use_roaming == -1)
-		options->use_roaming = 1;
+	options->use_roaming = 0;
 	if (options->visual_host_key == -1)
 		options->visual_host_key = 0;
 	if (options->ip_qos_interactive == -1)
diff --git a/ssh.c b/ssh.c
index 0ad82f0..7385462 100644
--- a/ssh.c
+++ b/ssh.c
@@ -1929,9 +1929,6 @@
 			fork_postauth();
 	}
 
-	if (options.use_roaming)
-		request_roaming();
-
 	return client_loop(tty_flag, tty_flag ?
 	    options.escape_char : SSH_ESCAPECHAR_NONE, id);
 }