f5_node also not idempotent

Start with the documentation example and the referenced f501sac.pp line 38, then reproduce the failure with puppet device -v --user=root. Trace the F5_pool resource handling for the existing pool member and use the reported REST 409 as the failure condition; done means subsequent agent runs apply without this error.

Attempting to follow the example in the docs for creating nodes/pool/virtual server structure, I found that subsequent puppet agent runs error out with the following message:

#> puppet device -v --user=root
Info: starting applying configuration to f501-sac at https://XXX.YYY.ZZZ.NNN:443/
Info: Retrieving pluginfacts
Info: Retrieving plugin
Info: Caching catalog for f501-sac
Info: Applying configuration version '1517876065'
Error: Could not set 'present' on ensure: REST failure: HTTP status code 409 detected. Body of failure is: {"code":409,"message":"01020066:3: The requested Pool Member (/Common/W3DR_API_pool /Common/W3DR_APIServer_1 80) already exists in partition Common.","errorStack":[],"apiError":3} at 38:/etc/puppetlabs/puppet/environments/production/modules/f5/manifests/f501sac.pp
Error: Could not set 'present' on ensure: REST failure: HTTP status code 409 detected. Body of failure is: {"code":409,"message":"01020066:3: The requested Pool Member (/Common/W3DR_API_pool /Common/W3DR_APIServer_1 80) already exists in partition Common.","errorStack":[],"apiError":3} at 38:/etc/puppetlabs/puppet/environments/production/modules/f5/manifests/f501sac.pp
Wrapped exception:
REST failure: HTTP status code 409 detected. Body of failure is: {"code":409,"message":"01020066:3: The requested Pool Member (/Common/W3DR_API_pool /Common/W3DR_APIServer_1 80) already exists in partition Common.","errorStack":[],"apiError":3}
Error: /Stage[main]/F5::F501sac/F5_pool[/Common/W3DR_API_pool]/ensure: change from absent to present failed: Could not set 'present' on ensure: REST failure: HTTP status code 409 detected. Body of failure is: {"code":409,"message":"01020066:3: The requested Pool Member (/Common/W3DR_API_pool /Common/W3DR_APIServer_1 80) already exists in partition Common.","errorStack":[],"apiError":3} at 38:/etc/puppetlabs/puppet/environments/production/modules/f5/manifests/f501sac.pp
Notice: Applied catalog in 0.97 seconds