python: emit more robust generated code to avoid self-inflicted crashes

[devdanzin]

Problem

Triaging a cereggii fleet, the non-target noise (after the SystemError-ignore change) was dominated by sessions the generated script kills itself in, not real target crashes: ~100 sigint and ~148 exitcode1. All are avoidable by emitting more robust code.

Fixes

1. sigint — bomb objects drawing KeyboardInterrupt. _BOMB_EXCEPTIONS included KeyboardInterrupt, a BaseException subclass. The generated call sites catch except Exception, so a bomb that draws it escapes and aborts the whole session (SIGINT) as a false crash. Dropped it — the pool is now Exception-only (bombs exist to exercise error paths, not to kill the interpreter). +regression test.

2. exitcode1 (AttributeError subset) — random module shadowed. The generated boilerplate did from random import …, random, …, rebinding the bare name random to the random() function and shadowing the random module that embedded tricky-object code imports and calls as random.randint(...) → AttributeError at module load. The name is never used bare in generated scripts, so we stop importing it; random now reliably resolves to the module. (Complements the existing _bomb_random alias that already hardened the core bomb source.)

3. exitcode1 (the rest) — unprotected argument construction. A call's arguments are constructed inline, before callMethod/callFunc runs — so a hostile literal argument (a set containing an unhashable object, a dict keyed on a __hash__ that raises, a bomb object) raises during argument construction, which callMethod's own handler can't catch, and escapes at module level. Wrap the whole res_X = callMethod(...) statement in try/except so the call is skipped and fuzzing continues. The thread/async call wrappers already protect their own argument construction; this closes the synchronous path.

Impact / validation

In the sampled fleet, every exitcode1 was a res_X = callMethod/callFunc(...) whose argument construction raised, and every sigint was a bomb KeyboardInterrupt — all now avoided. All three fixes verified at runtime; golden output regenerated and validated as parseable Python.

Tests

• New TestBombExceptionPool (pool stays Exception-only; _bomb_exc() never returns a BaseException-only type).
• Golden fakemod_seed1234.py regenerated (locks in the call wrapping + the random import).
• Full suite green (1038); ruff check + ruff format --check clean.

🤖 Generated with Claude Code