Skip flaky test_create_router_set_gateway_with_fixed_ip

test_create_router_set_gateway_with_fixed_ip starts by allocating an IP
from the public_network, then it deletes that IP (which releases the
IP back to the pool), then it tries to create a router with a fixed
external IP set to the IP value it got earlier.

But in the mean time, another test could have claimed the very same IP
because there's a fraction of time when the IP is again available. In
that case, the create router call fails with

Body: {"NeutronError": {"message": "IP address 172.24.5.2 already allocated
in subnet 41f6fb6a-f10d-4a9a-9b9b-235bbbde0891", "type":
"IpAddressAlreadyAllocated", "detail": ""}}

Change-Id: I9761b094351709f97e5b1524935d070796c64273
Related-Bug: #1676207
diff --git a/tempest/api/network/test_routers.py b/tempest/api/network/test_routers.py
index 742fe59..8df5248 100644
--- a/tempest/api/network/test_routers.py
+++ b/tempest/api/network/test_routers.py
@@ -243,6 +243,7 @@
     @test.requires_ext(extension='ext-gw-mode', service='network')
     @testtools.skipUnless(CONF.network.public_network_id,
                           'The public_network_id option must be specified.')
+    @decorators.skip_because(bug='1676207')
     def test_create_router_set_gateway_with_fixed_ip(self):
         # Don't know public_network_address, so at first create address
         # from public_network and delete