provisioners/ansible: fix galaxy paths on Windows

Close #6757 and update previous fix for #6740 (#6741).

See also these places where the same regexp is used to address similar
"Windows cases":

 - ec85548bd6/plugins/provisioners/chef/provisioner/chef_solo.rb (L99-L103)
 - ec85548bd6/plugins/guests/windows/cap/rsync.rb (L6-L9)

CHANGELOG.md

@@ -2,8 +2,8 @@
 
 BUG FIXES:
 
-  - provisioners/ansible_local: Fix error in `playbook` existence check when
-    running on a Windows host [GH-6740]
+  - provisioners/ansible_local: Fix errors in absolute paths to playbook or
+      galaxy resources when running on a Windows host [GH-6740, GH-6757]
 
 ## 1.8.1 (December 21, 2015)
 

plugins/provisioners/ansible/config/guest.rb

@@ -37,10 +37,7 @@ module VagrantPlugins
         protected
 
         def check_path(machine, path, test_args, error_message_key = nil)
-          remote_path = File.expand_path(path, @provisioning_path)
-
-          # Remove drive letter if running on a Windows host
-          remote_path = remote_path.gsub(/^[a-zA-Z]:/, "")
+          remote_path = Helpers::expand_path_in_unix_style(path, @provisioning_path)
 
           if machine.communicate.ready? && !machine.communicate.test("test #{test_args} #{remote_path}")
             if error_message_key

plugins/provisioners/ansible/helpers.rb

@@ -25,6 +25,12 @@ module VagrantPlugins
         shell_command += shell_arg.join(' ')
       end
 
+      def self.expand_path_in_unix_style(path, base_dir)
+        # Remove the possible drive letter, which is added
+        # by `File.expand_path` when running on a Windows host
+        File.expand_path(path, base_dir).sub(/^[a-zA-Z]:/, "")
+      end
+
       def self.as_list_argument(v)
         v.kind_of?(Array) ? v.join(',') : v
       end

plugins/provisioners/ansible/provisioner/base.rb

@@ -179,15 +179,16 @@ module VagrantPlugins
           end
         end
 
-        def get_galaxy_role_file(basedir)
-          File.expand_path(config.galaxy_role_file, basedir)
+        def get_galaxy_role_file(base_dir)
+          Helpers::expand_path_in_unix_style(config.galaxy_role_file, base_dir)
         end
 
-        def get_galaxy_roles_path(basedir)
+        def get_galaxy_roles_path(base_dir)
           if config.galaxy_roles_path
-            File.expand_path(config.galaxy_roles_path, basedir)
+            Helpers::expand_path_in_unix_style(config.galaxy_roles_path, base_dir)
           else
-            File.join(Pathname.new(config.playbook).expand_path(basedir).parent, 'roles')
+            playbook_path = Helpers::expand_path_in_unix_style(config.playbook, base_dir)
+            File.join(Pathname.new(playbook_path).parent, 'roles')
           end
         end