extension-release: establish compatibility between host file and extension-release file

The release file that accompanies the confext images needs to be
host compatible to be able to be merged into the host /etc/ directory.
This commit checks for version compatibility between the image file and
the host file.

src/core/namespace.c

@@ -1435,7 +1435,8 @@ static int apply_one_mount(
                                 host_os_release_version_id,
                                 host_os_release_sysext_level,
                                 /* host_sysext_scope */ NULL, /* Leave empty, we need to accept both system and portable */
-                                extension_release);
+                                extension_release,
+                                IMAGE_SYSEXT);
                 if (r == 0)
                         return log_debug_errno(SYNTHETIC_ERRNO(ESTALE), "Directory %s extension-release metadata does not match the root's", extension_name);
                 if (r < 0)
@@ -2155,7 +2156,7 @@ int setup_namespace(
         }
 
         if (n_extension_images > 0 || !strv_isempty(extension_directories)) {
-                r = parse_env_extension_hierarchies(&hierarchies);
+                r = parse_env_extension_hierarchies(&hierarchies, "SYSTEMD_SYSEXT_HIERARCHIES");
                 if (r < 0)
                         return r;
         }