powershell : warning: already initialized constant

Basic Info
Module Version: 2.1.4
Puppet Version: 4.10.10
OS Name/Version: Redhat 6.9

When using puppet device with multiple devices in one device config file, puppet is printing warnings to stderr about already initialized constant.

This can be fixed by using "unless defined".

Desired Behavior:

Not initialising contants multiple times. 

Actual Behavior:

$ puppet device --deviceconfig /etc/puppetlabs/puppet/device/device.conf
/opt/puppetlabs/puppet/cache/devices/device-x/lib/puppet/provider/exec/powershell.rb:30: warning: already initialized constant POWERSHELL_MODULE_UPGRADE_MSG
/opt/puppetlabs/puppet/cache/devices/device-x/lib/puppet/provider/exec/powershell.rb:30: warning: previous definition of POWERSHELL_MODULE_UPGRADE_MSG was here