gh-152373: Make pdb "until" step over a list comprehension with a breakpoint

[tonghuaroot]

until re-stops on a list comprehension (or single-line loop) line when a
breakpoint is set on it, because set_until does not record the frame and
line where the command was issued. next and step already record this
(gh-136160), so the existing same-line guard in dispatch_line applies to
them. This records it for set_until too, so until steps past the line like
next and step do.