Python3.15a3 breaks `%(default)x` in help strings

[alexprengere]

Bug report

Bug description:

Since the merge of #141940, the following is broken:

import argparse

parser = argparse.ArgumentParser()
parser.add_argument(
    "--foo",
    type=int,
    default=1234,
    help="0x%(default)x",
)

args = parser.parse_args()

It will trigger:

Traceback (most recent call last):
  File "/Users/aprengere/Dev/cpython/Lib/argparse.py", line 1792, in _check_help
    formatter._expand_help(action)
    ~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^
  File "/Users/aprengere/Dev/cpython/Lib/argparse.py", line 695, in _expand_help
    return help_string % params
           ~~~~~~~~~~~~^~~~~~~~
TypeError: %x format: an integer is required, not str

The reason is that now the values are "colored" (thus converted to str) before doing the actual interpolation using help_string % values.
If the expected type is not string (integer in this example), then the --help will fail.

I will try to fix this using a different approach for #141940

CPython versions tested on:

CPython main branch

Operating systems tested on:

macOS

[grayjk]

duplicate of #142950?

[alexprengere]

Yep, will close now 👍