If an `os/exec.Command` is passed non `*os.File` as an input/output, go
will create `os.Pipe`s and wait for their closure in `cmd.Wait()`. If
the code following this is responsible for closing `io.Pipe`s or other
handlers then on process death from context cancellation the `Wait` can
hang.
There are two possible solutions:
1. use `os.Pipe` as the input/output as `cmd.Wait` does not wait for these.
2. create a goroutine waiting on the context cancellation that will close the inputs.
This PR provides the second option - which is a simpler change that can
be more easily backported.
Closes#19448
Signed-off-by: Andrew Thornton <art27@cantab.net>
0dcc74a8a7