rhel-osp-director:  Introspection fails for a subset of BM nodes (Dell PowerEdge R320).

Environment:
instack-undercloud-4.0.0-2.el7ost.noarch

Steps to reproduce:
Run introspection.

Result:

[stack@undercloud ~]$ openstack baremetal introspection bulk start
Setting nodes for introspection to manageable...
Starting introspection of node: 9be1bece-24bf-456b-b6a1-b9cedaf88770
Starting introspection of node: b0b80a1a-d231-47b5-bf3b-cc6144825db9
Starting introspection of node: 7afb010a-7ca8-4d58-a91d-31391c9ce738
Starting introspection of node: 84251e42-8f93-4a38-91a5-1d3eb80d0e6e
Starting introspection of node: 05662a5e-4c07-44a9-a187-630dd6a8cf46
Starting introspection of node: 04b0a514-36d1-4505-bbdc-fc67bfce45d1
Starting introspection of node: df4092aa-7949-47db-811b-243073b76656
Starting introspection of node: 6f62f7b2-fe56-4a00-a9b3-3c758191ac57

Waiting for introspection to finish...
Introspection for UUID 9be1bece-24bf-456b-b6a1-b9cedaf88770 finished successfully.
Introspection for UUID 7afb010a-7ca8-4d58-a91d-31391c9ce738 finished successfully.
Introspection for UUID 84251e42-8f93-4a38-91a5-1d3eb80d0e6e finished successfully.
Introspection for UUID 05662a5e-4c07-44a9-a187-630dd6a8cf46 finished with error: Preprocessing hook validate_interfaces: No suitable interfaces found in {u'p1p1': {'ip': None, 'mac': u'00:0a:f7:7f:24:88'}, u'p1p2': {'ip': None, 'mac': u'00:0a:f7:7f:24:89'}, u'em1': {'ip': None, 'mac': u'44:a8:42:3b:2e:61'}, u'em2': {'ip': None, 'mac': u'44:a8:42:3b:2e:62'}}
Introspection for UUID 6f62f7b2-fe56-4a00-a9b3-3c758191ac57 finished with error: Preprocessing hook validate_interfaces: No suitable interfaces found in {u'p1p1': {'ip': None, 'mac': u'00:0a:f7:7f:24:5e'}, u'p1p2': {'ip': None, 'mac': u'00:0a:f7:7f:24:5f'}, u'em1': {'ip': None, 'mac': u'44:a8:42:3b:33:16'}, u'em2': {'ip': None, 'mac': u'44:a8:42:3b:33:17'}}
Introspection for UUID 04b0a514-36d1-4505-bbdc-fc67bfce45d1 finished with error: Preprocessing hook validate_interfaces: No suitable interfaces found in {u'p1p1': {'ip': None, 'mac': u'00:0a:f7:7f:24:9e'}, u'p1p2': {'ip': None, 'mac': u'00:0a:f7:7f:24:9f'}, u'em1': {'ip': None, 'mac': u'44:a8:42:3b:34:52'}, u'em2': {'ip': None, 'mac': u'44:a8:42:3b:34:53'}}
Introspection for UUID df4092aa-7949-47db-811b-243073b76656 finished with error: Preprocessing hook validate_interfaces: No suitable interfaces found in {u'p1p1': {'ip': None, 'mac': u'00:0a:f7:7f:24:96'}, u'p1p2': {'ip': None, 'mac': u'00:0a:f7:7f:24:97'}, u'em1': {'ip': None, 'mac': u'44:a8:42:3b:23:5d'}, u'em2': {'ip': None, 'mac': u'44:a8:42:3b:23:5e'}}
Introspection for UUID b0b80a1a-d231-47b5-bf3b-cc6144825db9 finished successfully.
Setting manageable nodes to available...
Node 9be1bece-24bf-456b-b6a1-b9cedaf88770 has been set to available.
Node b0b80a1a-d231-47b5-bf3b-cc6144825db9 has been set to available.
Node 7afb010a-7ca8-4d58-a91d-31391c9ce738 has been set to available.
Node 84251e42-8f93-4a38-91a5-1d3eb80d0e6e has been set to available.
Introspection completed with errors:
05662a5e-4c07-44a9-a187-630dd6a8cf46: Preprocessing hook validate_interfaces: No suitable interfaces found in {u'p1p1': {'ip': None, 'mac': u'00:0a:f7:7f:24:88'}, u'p1p2': {'ip': None, 'mac': u'00:0a:f7:7f:24:89'}, u'em1': {'ip': None, 'mac': u'44:a8:42:3b:2e:61'}, u'em2': {'ip': None, 'mac': u'44:a8:42:3b:2e:62'}}
6f62f7b2-fe56-4a00-a9b3-3c758191ac57: Preprocessing hook validate_interfaces: No suitable interfaces found in {u'p1p1': {'ip': None, 'mac': u'00:0a:f7:7f:24:5e'}, u'p1p2': {'ip': None, 'mac': u'00:0a:f7:7f:24:5f'}, u'em1': {'ip': None, 'mac': u'44:a8:42:3b:33:16'}, u'em2': {'ip': None, 'mac': u'44:a8:42:3b:33:17'}}
04b0a514-36d1-4505-bbdc-fc67bfce45d1: Preprocessing hook validate_interfaces: No suitable interfaces found in {u'p1p1': {'ip': None, 'mac': u'00:0a:f7:7f:24:9e'}, u'p1p2': {'ip': None, 'mac': u'00:0a:f7:7f:24:9f'}, u'em1': {'ip': None, 'mac': u'44:a8:42:3b:34:52'}, u'em2': {'ip': None, 'mac': u'44:a8:42:3b:34:53'}}
df4092aa-7949-47db-811b-243073b76656: Preprocessing hook validate_interfaces: No suitable interfaces found in {u'p1p1': {'ip': None, 'mac': u'00:0a:f7:7f:24:96'}, u'p1p2': {'ip': None, 'mac': u'00:0a:f7:7f:24:97'}, u'em1': {'ip': None, 'mac': u'44:a8:42:3b:23:5d'}, u'em2': {'ip': None, 'mac': u'44:a8:42:3b:23:5e'}}