create path when parent of file to be written does not exist

+ usage for frappy command

install.py

@@ -312,6 +312,7 @@ def write_when_new(filename, content, as_root=False, ignore_reduction=False):
             return False
     if doit:
         if lines:
+            Path(filename).parent.mkdir(parents=True, exist_ok=True)
             with tempfile.NamedTemporaryFile('w') as fil:
                 fil.write(content)
                 fil.flush()