http_client: Fix GitHub downloads failing if the destination path exists (#51548)

cc
https://github.com/zed-industries/zed/pull/45428#issuecomment-4060334728

Release Notes:

- N/A *or* Added/Fixed/Improved ...
e482301908Lukas Wirth committed on 3/14/2026, 2:17:09 PM· committed by GitHubparente79429b
1 file changedLine totals unavailable