[FIX] Do take nested rooted fs paths into account in computation of s…

…tore_fname. Code by @lmignon - Laurent Mignon (ACSONE)

fs_attachment/models/ir_attachment.py

@@ -457,7 +457,20 @@ def _enforce_meaningful_storage_filename(self) -> None:
             # we need to update the store_fname with the new filename by
             # calling the write method of the field since the write method
             # of ir_attachment prevent normal write on store_fname
-            attachment._force_write_store_fname(f"{storage}://{new_filename_with_path}")
+
+            # rooted_dir path computation...
+            # done by @lmignon - Laurent Mignon (ACSONE)
+            # there could be a nested rooted dir in the fs path - we do compute it here
+            # and remove it from the new_filename if it does exists
+            rooted_paths = []
+            rooted_dir_fs = fs
+            while rooted_dir_fs and hasattr(rooted_dir_fs, "path"):
+                rooted_paths.append(rooted_dir_fs.path)
+                rooted_dir_fs = getattr(rooted_dir_fs, "fs", None)
+            rooted_paths.reverse()
+            rooted_path = "/".join(rooted_paths)
+            new_filename = new_filename_with_path.replace(rooted_path, "")
+            attachment._force_write_store_fname(f"{storage}://{new_filename}")
             self._fs_mark_for_gc(attachment.store_fname)
 
     def _force_write_store_fname(self, store_fname):