sort in editor (ALT-T) without arguments stopped working

[sxmboer2]

In the editor, select a block of text and hit ALT-T does nothing when the argument is empty.
when options are used, e.g. "+0", "-r", "-u", sorting works fine.

midnightcommander>LC_MESSAGES=C ./src/mc -V
GNU Midnight Commander 4.8.28-72-g255502756
Built with GLib 2.70.4
Built with S-Lang 2.3.2 with terminfo database
Built with libssh2 1.10.0
With builtin Editor
With subshell support as default
With support for background operations
With mouse support on xterm and Linux console
With support for X11 events
With internationalization support
With multiple codepages support
With ext2fs attributes support
Virtual File Systems:
 cpiofs, tarfs, sfs, extfs, ftpfs, sftpfs, fish
Data types:
 char: 8; int: 32; long: 64; void *: 64; size_t: 64; off_t: 64;

midnightcommander>LC_MESSAGES=C ./src/mc -F
Home directory: /root
Profile root directory: /root

[System data]
    Config directory: /usr/local/etc/mc/
    Data directory:   /usr/local/share/mc/
    File extension handlers: /usr/local/libexec/mc/ext.d/
    VFS plugins and scripts: /usr/local/libexec/mc/
	extfs.d:        /usr/local/libexec/mc/extfs.d/
	fish:           /usr/local/libexec/mc/fish/

[User data]
    Config directory: /root/.config/mc/
    Data directory:   /root/.local/share/mc/
	skins:          /root/.local/share/mc/skins/
	extfs.d:        /root/.local/share/mc/extfs.d/
	fish:           /root/.local/share/mc/fish/
	mcedit macros:  /root/.local/share/mc/mc.macros
	mcedit external macros: /root/.local/share/mc/mcedit/macros.d/macro.*
    Cache directory:  /root/.cache/mc/

midnightcommander>src/mc --configure-options
 'PKG_CONFIG_PATH=/usr/local/lib64/pkgconfig:/usr/local/share/pkgconfig:/usr/local/lib/pkgconfig:/usr/lib64/pkgconfig:/usr/share/pkgconfig'