Description of problem:

I creates SLES operation system and assigned AutoYaST default iPXE template to it
now if I want to enable build mode of SLES host I get this error:

The following errors may prevent a successful build:
Templates
Failure parsing AutoYaST default iPXE: undefined method `medium_uri' for #<Foreman::Renderer::Scope::Provisioning:0x000000000b3e9418> Did you mean? medium_url media_url. 


This is AutoYaST default iPXE template:

#!gpxe
<%#
kind: iPXE
name: AutoYaST default iPXE
model: ProvisioningTemplate
oses:
- SLES
- OpenSUSE
%>

<% boot_files_uris = @host.operatingsystem.boot_files_uri(medium_provider) -%>
<% kernel = boot_files_uris[0] -%>
<% initrd = boot_files_uris[1] -%>

kernel <%= kernel %> initrd=initrd.img splash=silent install=<%= medium_uri %> autoyast=<%= foreman_url('provision') %> text-mode=1 useDHCP=1
initrd <%= initrd %>
boot

diff of 6.4 and 6.5 version of the template:

--- 6.4	2018-11-28 08:19:36.726269741 +0100
+++ 6.5	2018-11-28 08:19:49.254340534 +0100
@@ -8,10 +8,10 @@
 - OpenSUSE
 %>
 
-<% boot_files_uris = @host.operatingsystem.boot_files_uri(@host.medium,@host.architecture) -%>
+<% boot_files_uris = @host.operatingsystem.boot_files_uri(medium_provider) -%>
 <% kernel = boot_files_uris[0] -%>
 <% initrd = boot_files_uris[1] -%>
 
-kernel <%= kernel %> initrd=initrd.img splash=silent install=<%=@host.os.medium_uri(@host)%> autoyast=<%= foreman_url('provision') %> text-mode=1 useDHCP=1
+kernel <%= kernel %> initrd=initrd.img splash=silent install=<%= medium_uri %> autoyast=<%= foreman_url('provision') %> text-mode=1 useDHCP=1
 initrd <%= initrd %>
 boot



Version-Release number of selected component (if applicable):
Sat 6.5 snap 5