Description of problem:

oo-accept-node inconsistently checks for the non-existence of /sbin/ip in the tests that use it: 
find_ext_net_dev rescues if there is a Errno::ENOENT exception whereas check_node_public_resolution fails ungracefully with an unrescued exception.


How reproducible:

Completely.


Steps to Reproduce:

1. Install an OpenShift Enterprise PaaS with 1 node.

2. Move /sbin/ip to /sbin/ip on the node from Step 1.

3. Run oo-accept-node -v on the node.


Actual results:

At Step 3, oo-accept-node rescues gracefully in the find_ext_net_dev test but subsequently fails ungracefully with an unrescued exception in the check_node_public_resolution test:

    # oo-accept-node -v
    INFO: using default accept-node extensions
    INFO: loading node configuration file /etc/openshift/node.conf
    INFO: loading resource limit file /etc/openshift/resource_limits.conf
    INFO: finding external network device
    FAIL: SEVERE: could not find ip command (/sbin/ip).
    INFO: checking node public hostname resolution
    /usr/sbin/oo-accept-node:318:in ``': No such file or directory - /sbin/ip addr show scope global (Errno::ENOENT)
            from /usr/sbin/oo-accept-node:318:in `check_node_public_resolution'
            from /usr/sbin/oo-accept-node:914:in `<main>'
    #


Expected results:

At Step 3, oo-accept-node should always gracefully handle Errno::ENOENT errors:

    # oo-accept-node -v
    INFO: using default accept-node extensions
    INFO: loading node configuration file /etc/openshift/node.conf
    INFO: loading resource limit file /etc/openshift/resource_limits.conf
    INFO: finding external network device
    FAIL: SEVERE: could not find ip command (/sbin/ip).
    INFO: checking node public hostname resolution
    FAIL: SEVERE: could not find ip command (/sbin/ip).
    INFO: checking selinux status
    INFO: checking selinux openshift-origin policy
    INFO: checking selinux booleans
    INFO: checking package list
    INFO: checking services
    INFO: checking kernel semaphores >= 512
    INFO: checking cgroups configuration
    INFO: checking cgroups processes
    INFO: find district uuid: 538646d0eaa253c5da000001
    INFO: determining node uid range: 1000 to 6999
    INFO: traffic control not enabled in /etc/openshift/node.conf, set TRAFFIC_CONTROL_ENABLED=true to enable
    INFO: checking filesystem quotas
    INFO: checking quota db file selinux label
    INFO: checking 5 user accounts
    INFO: checking application dirs
    INFO: checking system httpd configs
    INFO: checking cartridge repository
    2 ERRORS
    #