(PUP-5743) adapt to new environment name semantics

Since applying a fix for PUP-5522 (puppet 3.8.5 and 4.3.2) puppet symbolizes environment names
internally. The catalog cache needs to assume that the facts and other args do not change between
runs, so we have to mirror this here. Puppet versions before the change require a string as environment
name, or they fail with "Unsupported data type: 'Symbol' on node xyz"
See rodjek#354 and PUP-5743 for discussion of this

lib/rspec-puppet/support.rb

@@ -9,7 +9,18 @@ def subject
     end
 
     def environment
-      'rp_env'
+      # unfreeze PUPPETVERSION because of https://github.com/bundler/bundler/issues/3187
+      ver = Gem::Version.new("#{Puppet::PUPPETVERSION}")
+      # Since applying a fix for PUP-5522 (puppet 3.8.5 and 4.3.2) puppet symbolizes environment names
+      # internally. The catalog cache needs to assume that the facts and other args do not change between
+      # runs, so we have to mirror this here. Puppet versions before the change require a string as environment
+      # name, or they fail with "Unsupported data type: 'Symbol' on node xyz"
+      # See https://github.com/rodjek/rspec-puppet/pull/354 and PUP-5743 for discussion of this
+      if (Gem::Version.new('3.8.5') <= ver && ver < Gem::Version.new('4.0.0')) || Gem::Version.new('4.3.2') <= ver
+        :rp_env
+      else
+        'rp_env'
+      end
     end
 
     def load_catalogue(type)