existing behavior of
:=
and
:[range]=
are unchanged. `|` is still allowed with this usage.
However,
:=p
and similar are changed in a way which could be construed as a breaking
change. Allowing |ex-flags| for := in the first place was a mistake as
any form of := DOES NOT MOVE THE CURSOR. So it would print one line number
and then print a completely different line contents after that.