Fix os_transport_url with single hosts array

If an array with a single host is passed into the hosts param, the
function was erroring because the host was getting converted to a string
when it was checking for bracketing for ipv6. This change checks the
type and fixes the case where a single host is being passed so it
continues to function.

Change-Id: I91b9959a6f71b4e6885e55a568116cc28cf16ddd
Closes-Bug: #1650042

lib/puppet/parser/functions/os_transport_url.rb

@@ -113,6 +113,9 @@ EOS
 
   if v.include?('hosts')
     hosts = function_normalize_ip_for_uri([v['hosts']])
+    # normalize_ip_for_uri may return a string, so check that we still have an
+    # array
+    hosts = [hosts] if hosts.kind_of?(String)
     hosts = hosts.map{ |h| "#{h}:#{v['port']}" } if v.include?('port')
     if parts.include?(:userinfo)
       parts[:hostinfo] = hosts.map { |h| "#{parts[:userinfo]}@#{h}" }.join(',')

spec/functions/os_transport_url_spec.rb

@@ -37,6 +37,19 @@ describe 'os_transport_url' do
 
   context 'creates the correct transport URI' do
 
+    it 'with a single host array for hosts' do
+      is_expected.to run.with_params({
+          'transport'    => 'rabbit',
+          'hosts'        =>  [ '127.0.0.1' ],
+          'port'         => '5672',
+          'username'     => 'guest',
+          'password'     => 's3cr3t',
+          'virtual_host' => 'virt',
+          'ssl'          => '1',
+          'query'        => { 'read_timeout' => '60' },
+        }).and_return('rabbit://guest:s3cr3t@127.0.0.1:5672/virt?read_timeout=60&ssl=1')
+    end
+
     it 'with all params for a single host' do
       is_expected.to run.with_params({
           'transport'    => 'rabbit',