u+1 no longer?

Umpteen years ago, I used to be able to type
  u+1
as a gdb command, and it would be interpreted as "until +1", since it
couldn't mean anything else. At some point this turned into an error,
"Undefined command".

It seems there is no way to actually define such a command, e.g.,
"define u+1" in .gdbinit gets "Junk in argument list".

Maybe there's a better way to do this now, but I seem to use that
command an awful lot, namely to step through a loop the first time and
then "until" beyond the loop instead of stepping through again.

Clearly it's not a big deal, but since the space is seemingly
unnecessary and useless, I'd just as soon not have to type it.

Can the old intuitive behavior be restored?  Or, alternatively, if a u+1
command could be defined, that'd be good too.

Thanks,
Karl