commit 9543e45afe0746ac1c9c10e4f78f43264fd288b4
Author: Dan Williams <dcbw@redhat.com>
Date:   Mon Oct 7 11:40:16 2013 -0500

    core: allow IPv4 to proceed if IPv6 is globally disabled but set to "auto" (rh #1012151)
    
    If the user disabled IPv6 support in the kernel with "ipv6.disable=1" on the
    kernel boot line, then any attempts to open IPv6 sockets (which libndp does)
    will fail.  This failed the entire connection, even if IPv6's "may-fail"
    property was TRUE.  Instead, just fail IPv6 and allow IPv4 to proceed.  If
    IPv4 fails or is disabled, then other logic will fail the entire connection.

diff --git a/src/devices/nm-device.c b/src/devices/nm-device.c
index d99b3d7..6810afc 100644
--- a/src/devices/nm-device.c
+++ b/src/devices/nm-device.c
@@ -3329,8 +3329,8 @@ act_stage3_ip6_config_start (NMDevice *self,
 	if (   strcmp (method, NM_SETTING_IP6_CONFIG_METHOD_AUTO) == 0
 	    || strcmp (method, NM_SETTING_IP6_CONFIG_METHOD_LINK_LOCAL) == 0) {
 		if (!addrconf6_start (self)) {
-			*reason = NM_DEVICE_STATE_REASON_IP_CONFIG_UNAVAILABLE;
-			ret = NM_ACT_STAGE_RETURN_FAILURE;
+			/* IPv6 might be disabled; allow IPv4 to proceed */
+			ret = NM_ACT_STAGE_RETURN_STOP;
 		} else
 			ret = NM_ACT_STAGE_RETURN_POSTPONE;
 	} else if (strcmp (method, NM_SETTING_IP6_CONFIG_METHOD_DHCP) == 0) {