pdb: "until" does not step over a list comprehension with a breakpoint set on it

Bug report

When a breakpoint is set on a line that holds a list comprehension (or any
single-line loop), the until command stops on that same line again on every
iteration instead of moving past it.

Reproduction:

# repro.py
def f():
    lst = [i for i in range(10)]
    for i in lst: pass

f()

$ python -m pdb repro.py
> repro.py(1)<module>()
-> def f():
(Pdb) break 2
Breakpoint 1 at repro.py:2
(Pdb) continue
> repro.py(2)f()
-> lst = [i for i in range(10)]
(Pdb) until
> repro.py(2)f()
-> lst = [i for i in range(10)]
(Pdb) until
> repro.py(2)f()
-> lst = [i for i in range(10)]

until keeps stopping on line 2, once per comprehension element.

Expected: until moves past the comprehension to the next line, the way next
and step already do (gh-136057, gh-136160). This also matches gdb, which
pdb's until is borrowed from: there, until steps past a single-line loop
to the next line even with a breakpoint set on it, instead of stopping on each
iteration.

I have a small fix for this and can open a PR.

Linked PRs

• gh-152374

从 pdb 入口点开始，使用 repro.py 重现该行为，在列表推导式所在行设置断点，并反复运行 until。按照 issue 中的描述，将 until 与 next 和 step 进行比较。当 until 前进到下一行，而不是在每个推导式元素处停止时，即表示完成；已记录一个关联的 PR。