command: stop restarting playback when writing to playlist-pos

e9e93b4dbe added a warning about writing
the same value to the playlist-pos property that in the future it would
stop restarting playback. Instead, you should use the
playlist-play-index command for that. Well go ahead and drop the old
deprecated behavior now and do what wm4 wanted this to do: just ignore
if the same value is written again.

DOCS/interface-changes.rst

@@ -79,6 +79,8 @@ Interface changes
     - remove deprecated `drop-frame-count` and `vo-drop-frame-count` property aliases
     - remove the ability to write to the `display-fps` property (use `override-display-fps`
       instead)
+    - writing the current value to playlist-pos will no longer restart playback (use
+      `playlist-play-index` instead)
  --- mpv 0.36.0 ---
     - add `--target-contrast`
     - Target luminance value is now also applied when ICC profile is used.

DOCS/man/input.rst

@@ -2772,10 +2772,9 @@ Property list
     (Before mpv 0.33.0, instead of returning -1, this property was unavailable
     if no playlist entry was current.)
 
-    Writing the current value back to the property is subject to change.
-    Currently, it will restart playback of the playlist entry. But in the
-    future, writing the current value will be ignored. Use the
-    ``playlist-play-index`` command to get guaranteed behavior.
+    Writing the current value back to the property will have no effect.
+    Use ``playlist-play-index`` to restart the playback of the current entry if
+    desired.
 
 ``playlist-pos-1`` (RW)
     Same as ``playlist-pos``, but 1-based.

player/command.c

@@ -3037,11 +3037,8 @@ static int mp_property_playlist_pos_x(void *ctx, struct m_property *prop,
     }
     case M_PROPERTY_SET: {
         int pos = *(int *)arg - base;
-        if (pos >= 0 && playlist_entry_to_index(pl, pl->current) == pos) {
-            MP_WARN(mpctx, "Behavior of %s when writing the same value will "
-                    "change (currently restarts, it will stop doing this).\n",
-                    prop->name);
-        }
+        if (pos >= 0 && playlist_entry_to_index(pl, pl->current) == pos)
+            return M_PROPERTY_OK;
         mp_set_playlist_entry(mpctx, playlist_entry_from_index(pl, pos));
         return M_PROPERTY_OK;
     }