Temporary workaround using tjim's discovery above - change the key definitions for "M-<" and "home" in
modules/bindings/default/basic-commands.js thus:

// define_key(keymap, "M-<","scroll-top-left");
define_key(keymap, "M-<","cmd_scrollTop");

// define_key(keymap, "home","scroll-top-left");
define_key(keymap, "home","cmd_scrollTop");