Fix a regression introduced by commit c2f4404fca ("threading: enable
filtering of server-side threads"). Prior to this commit, a :sort
command (no args) would clear out the current sort criteria (or rather,
apply the value from the config). Restore this functionality.
Fixes: c2f4404fca ("threading: enable filtering of server-side threads")
Reported-by: akspecs <akspecs@gmail.com>
Signed-off-by: Tim Culverhouse <tim@timculverhouse.com>
Acked-by: Robin Jarry <robin@jarry.cc>