filed: ldap - improve path handling on restore

Previously the destination dn when restoring an ldap object was
generated in a way that made it really hard to restore do a different
location.
This patch replaces the parser with a much more relaxed approach that
accepts different syntaxes. The new behaviour uses every path component
that contains an equals-sign (=) and builds a DN out of these.

(backport of commit 35451a0)

core/src/plugins/filed/BareosFdPluginLDAP.py

@@ -430,12 +430,20 @@ def get_next_file_to_backup(self, context, savepkt):
         return bRCs["bRC_OK"]
 
     def set_new_dn(self, fname):
-        path = fname[: -len("/ldif.data")]
-        # Convert the PATH into a DN e.g. reverse the elements.
-        path_sliced = path.split("/")
-        new_dn = "".join([element + "," for element in reversed(path_sliced)])
-        # Remove the ',@LDAP,' in the DN which is an internal placeholder
-        self.dn = new_dn.replace(",@LDAP,", "")
+        """
+        Generate a LDAP DN based on provided filename and path.
+
+        1. split filename into path components
+        2. reverse the list
+        3. filter out anything without an equals sign("=")
+        4. join components into comma-separated string
+        """
+        self.dn = ",".join(
+            filter(
+                lambda x: "=" in x,
+                reversed(fname.split("/")),
+            )
+        )
 
     def has_next_file(self, context):
         # See if we are currently handling the LDIF file or