Fixes#13748
Diagnostic for that issue with this change:
```
warning: spawned process is not `wait()`ed on in all code paths
--> x.rs:167:19
|
167 | let mut cmd = cmd.unwrap();
| ^^^^^^^^^^^^
|
note: no `wait()` call exists on the code path to this early return
--> x.rs:178:47
|
178 | std::io::ErrorKind::BrokenPipe => return Some(0),
| ^^^^^^^^^^^^^^
note: `wait()` call exists, but it is unreachable due to the early return
--> x.rs:185:10
|
185 | Some(cmd.wait().unwrap().code().unwrap()) // <-- wait()!
| ^^^
= help: consider calling `.wait()` in all code paths
= note: not doing so might leave behind zombie processes
= note: see https://doc.rust-lang.org/stable/std/process/struct.Child.html#warning
```
Instead of saying "wait() is **never** called", it now says it's not
called by all code paths and points out the early return in particular.
changelog: none