gh-149619 Fix _remote_debugging permissions error on Linux

[ivonastojanovic]

When running profiling on Linux without sudo, attempts to read process memory would fail with the misleading error 'Failed to find the PyRuntime section in process on Linux platform'.

The actual issue is a permissions error because profiling was not run with sudo. We were clearing the exception on Linux when trying to read memory, instead, we should bubble up the permissions error and show it properly.

• Issue: _remote_debugging: incorrect error for process_vm_readv() w/ EPERM when detecting the cookie #149619

[ivonastojanovic]

cc @maurycy

[maurycy]

@ivonastojanovic

I cannot click "Approve" but it's great. 🎉 The issue is gone. 🌬️

Two side comments!

My hunch is that there's still something subtle around error propagation (likely: EACCES propagation) but I cannot catch any!

I spent some time thinking on how to test it. What do you think about:

@unittest.skipUnless(
    sys.platform == "linux"
    and Path("/proc/sys/kernel/yama/ptrace_scope").exists()
    and int(Path("/proc/sys/kernel/yama/ptrace_scope").read_text()) >= 1,
    "needs Linux with ptrace_scope >= 1"
)

This feels so fragile!