Restructure the package provider to use the candidate_version accessor vs the variable directly.

This allows us to delay loading the candidate_version until it's actually needed.

For example, it's not needed if we didn't specify a version, we're doing an install, and we already have a version installed.

If we do this, then we can possibly speed up the other providers because they don't have to look up a candidate version, only
an actual installed version. Some can do this via disk instead of via the package maintainers, and this makes it go faster.

Author: ctennis

chef/lib/chef/provider/package.rb

@@ -36,25 +36,24 @@ def initialize(node, new_resource)
       end
 
       def action_install  
-        # First, select what version we should be using
-        install_version = @new_resource.version
-        install_version ||= @candidate_version
-        
-        unless install_version
-          raise(Chef::Exceptions::Package, "No version specified, and no candidate version available!")
-        end
-        
         do_package = false
         # If it's not installed at all, install it
         if @current_resource.version == nil
           do_package = true
+          install_version = candidate_version
         # If we specified a version, and it's not the current version, move to the current version
         elsif @new_resource.version != nil
+          install_version = @new_resource.version
           if @new_resource.version != @current_resource.version
             do_package = true
           end
         end
+
         if do_package
+          unless install_version
+            raise(Chef::Exceptions::Package, "No version specified, and no candidate version available!")
+          end
+
           Chef::Log.info("Installing #{@new_resource} version #{install_version}")
 
           # We need to make sure we handle the preseed file
@@ -70,10 +69,10 @@ def action_install
       end
 
       def action_upgrade
-        if @current_resource.version != @candidate_version
+        if @current_resource.version != candidate_version
           orig_version = @current_resource.version || "uninstalled"
-          Chef::Log.info("Upgrading #{@new_resource} version from #{orig_version} to #{@candidate_version}")
-          status = upgrade_package(@new_resource.package_name, @candidate_version)
+          Chef::Log.info("Upgrading #{@new_resource} version from #{orig_version} to #{candidate_version}")
+          status = upgrade_package(@new_resource.package_name, candidate_version)
           if status
             @new_resource.updated = true
           end