create target backup directory when needed

repo_sync.py

@@ -61,6 +61,10 @@ def backup() -> bool:
     return subprocess.run(cmd, cwd=HOME).returncode == 0
 
 
+def make_target_dir():
+    return subprocess.run(['ssh', CENTRAL, 'mkdir', '-p', REMOTE_DIR]).returncode == 0
+
+
 def restore() -> bool:
     # "/./" marks where the relative path starts, so with -R each subtree
     # lands under $HOME with its original relative path
@@ -110,6 +114,7 @@ def cmd_backup() -> None:
         cwd=HOME, stdout=subprocess.PIPE, text=True,
     )
     threading.Thread(target=reader, args=(watcher,), daemon=True).start()
+    make_target_dir()
     try:
         while True:
             if watcher.poll() is not None: