Robustness of the persistent option

[lstrojny]

When the persistent mode is used but PHP_INI_SCAN_DIR is ignored by the target binary, xdebug-handler will not notice that it didn't succeed. I am wondering if xdebug-handler should somehow detect that there was a problem.

See https://github.com/NixOS/nixpkgs/pull/221845 for a case where that happened because of the specific way nix packages PHP.

[johnstevenson]

Why does the binary ignore PHP_INI_SCAN_DIR?

[lstrojny]

@johnstevenson frankly, it looks like a bug to me. That’s also why the issue here is more of a question than an actual issue report. I was wondering if xdebug-handler should be hardened to detect such an environment.