[3.14] gh-148615: Handle `--` separator in pdb argument parsing (GH-1… (#149442)

[3.14] gh-148615: Handle `--` separator in pdb argument parsing (GH-148624)
(cherry picked from commit 970b0433f498fd0d048b1f50229a7f0fb4d9e07a)

Co-authored-by: Shrey Naithani <shrey.naithani@shelllite.tech>