diff --git a/lib/neutron_plugins/linuxbridge_agent b/lib/neutron_plugins/linuxbridge_agent
index d0de2f5..0c8ccb8 100644
--- a/lib/neutron_plugins/linuxbridge_agent
+++ b/lib/neutron_plugins/linuxbridge_agent
@@ -62,7 +62,9 @@
         LB_INTERFACE_MAPPINGS=$PHYSICAL_NETWORK:$LB_PHYSICAL_INTERFACE
     fi
     if [[ "$PUBLIC_BRIDGE" != "" ]] && [[ "$PUBLIC_PHYSICAL_NETWORK" != "" ]]; then
-        iniset /$Q_PLUGIN_CONF_FILE linux_bridge bridge_mappings "$PUBLIC_PHYSICAL_NETWORK:$PUBLIC_BRIDGE"
+        if is_service_enabled q-l3 || is_service_enabled neutron-l3; then
+            iniset /$Q_PLUGIN_CONF_FILE linux_bridge bridge_mappings "$PUBLIC_PHYSICAL_NETWORK:$PUBLIC_BRIDGE"
+        fi
     fi
     if [[ "$LB_INTERFACE_MAPPINGS" != "" ]]; then
         iniset /$Q_PLUGIN_CONF_FILE linux_bridge physical_interface_mappings $LB_INTERFACE_MAPPINGS
diff --git a/lib/nova_plugins/hypervisor-libvirt b/lib/nova_plugins/hypervisor-libvirt
index 167ab6f..f3c8add 100644
--- a/lib/nova_plugins/hypervisor-libvirt
+++ b/lib/nova_plugins/hypervisor-libvirt
@@ -105,6 +105,16 @@
     if [[ "$ENABLE_FILE_INJECTION" == "True" ]] ; then
         if is_ubuntu; then
             install_package python-guestfs
+            # NOTE(andreaf) Ubuntu kernel can only be read by root, which breaks libguestfs:
+            # https://bugs.launchpad.net/ubuntu/+source/linux/+bug/759725)
+            INSTALLED_KERNELS="$(ls /boot/vmlinuz-*)"
+            for kernel in $INSTALLED_KERNELS; do
+                STAT_OVERRIDE="root root 644 ${kernel}"
+                # unstack won't remove the statoverride, so make this idempotent
+                if [[ ! $(dpkg-statoverride --list | grep "$STAT_OVERRIDE") ]]; then
+                    sudo dpkg-statoverride --add --update $STAT_OVERRIDE
+                fi
+            done
         elif is_fedora || is_suse; then
             install_package python-libguestfs
         fi
diff --git a/stack.sh b/stack.sh
index 9c63f5f..05a7666 100755
--- a/stack.sh
+++ b/stack.sh
@@ -1386,7 +1386,15 @@
 
 # Do this late because it requires compute hosts to have started
 if is_service_enabled n-api; then
-    create_cell
+    if is_service_enabled n-cpu; then
+        create_cell
+    else
+        # Some CI systems like Hyper-V build the control plane on
+        # Linux, and join in non Linux Computes after setup. This
+        # allows them to delay the processing until after their whole
+        # environment is up.
+        echo_summary "SKIPPING Cell setup because n-cpu is not enabled. You will have to do this manually before you have a working environment."
+    fi
 fi
 
 # Bash completion