Zipapp doesn't forward signals (SIGTERM and friends) to the process, resulting in orphaned processes and no cleanup

# 🐞 bug report

### Affected Rule

The issue is caused by the rule: `py_binary`

### Is this a regression?

Yes, the previous version in which this bug was not present was: ....

Unsure

### Description

A clear and concise description of the problem...

When running a `py_binary` zipapp (E.g. `bazel build --build_python_zip `) signals such as `SIGTERM` aren't forwarded to the binary itself, meaning the process doesn't get a chance to clean up.

I suspect https://github.com/bazel-contrib/rules_python/blob/25ad57c85f0094889520486cd9a5738278fd0541/python/private/zipapp/zip_main_template.py#L279-L281 is the source of the issue

## 🔬 Minimal Reproduction

Given

```
import signal

signal.signal(signal.SIGTERM, lambda _1, _2: print("SIGTERM"))

while True:
pass
```

Then `bazel run ` and a `kill -s TERM ` will print `SIGTERM`. But `bazel build --build_python_zip ` followed by a `python .zip` and a `kill -s TERM ` (of the outer process) results in the process being terminated and the underlying process being orphaned 💔

## 🔥 Exception or Error

N/A

## 🌍 Your Environment

**Operating System:**

  

x64 Ubuntu

  

**Output of `bazel version`:**

  

Build label: 8.6.0

Build target: @@//src/main/java/com/google/devtools/build/lib/bazel:BazelServer

Build time: Thu Feb 26 19:55:20 2026 (1772135720)

Build timestamp: 1772135720

Build timestamp as int: 1772135720

  

**Rules_python version:**

  

1.9.0

  

**Anything else relevant?**

Start with python/private/zipapp/zip_main_template.py around lines 279-281, then reproduce the issue with the provided signal-handling Python program. Compare `bazel run` with executing the built zipapp and verify that SIGTERM reaches the underlying process and allows cleanup without leaving it orphaned.

Do mô hình lập chỉ mục viết ra từ nội dung của issue.