Merge ~kissiel/plainbox-provider-resource:nvme-rotation-fix into plainbox-provider-resource:master

[Maciej Kisielewski]

check if 'rotational' exists before opening for block devices

Which fixes a problem that occurred when running block_device job on NVMe drives.

[Sylvain Pineau (sylvain-pineau)]

+1

review: Approve

diff --git a/bin/block_device_resource b/bin/block_device_resource
index 1eed9b7..8e97ffb 100755
--- a/bin/block_device_resource
+++ b/bin/block_device_resource
@@ -58,8 +58,10 @@ def device_rotation(name):
     Check the device queue/rotational parameter to determine if it's a spinning
     device or a non-spinning device, which indicates it's an SSD.
     """
-    with open('/sys/block/%s/device/block/%s/queue/rotational' % (name, name),
-              "rt") as f:
+    path = '/sys/block/{0}/device/block/{0}/queue/rotational'.format(name)
+    if not os.path.exists(path):
+        return 'no'
+    with open(path, "rt") as f:
         if f.read(1) == '1':
             return 'yes'