Use of CLONE_PIDFD for forkfd interacts badly with debugging

#include <QCoreApplication>
#include <QProcess>
#include <QDebug>

int main(int argc, char *argv[])
{
  QCoreApplication a(argc, argv);

  QProcess p;
  p.start("/bin/ls", {"--version"});
  p.waitForStarted();
  p.waitForFinished();

  qDebug() << p.readAllStandardOutput();

  return 0;
}

$ gdb ./untitled -ex run -ex quit -batch
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
[Detaching after fork from child process 89575]
"ls (GNU coreutils) 8.30\nCopyright (C) 2018 Free Software Foundation, Inc.\nLicense GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>.\nThis is free software: you are free to change and redistribute it.\nThere is NO WARRANTY, to the extent permitted by law.\n\nWritten by Richard M. Stallman and David MacKenzie.\n"
[Inferior 1 (process 89571) exited normally]

$ gdb ./untitled -ex run -ex quit -batch

[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
[New Thread 0x7ffff50ce780 (LWP 88899)]
process 88895 is executing new program: /usr/bin/ls
warning: Probes-based dynamic linker interface failed.
Reverting to original interface.
 
Thread 2 received signal SIGSEGV, Segmentation fault.
[Switching to LWP 88899]
0x00007ffff7fd37a5 in ?? () from /lib64/ld-linux-x86-64.so.2
A debugging session is active.

Inferior 1 [process 88895] will be killed.

(lldb) target create "/tmp/untitled/untitled"
Current executable set to '/tmp/untitled/untitled' (x86_64).
(lldb) r
Process 396885 launched: '/tmp/untitled/untitled' (x86_64)
Process 396885 stopped and restarted: thread 1 received signal: SIGCHLD
"ls (GNU coreutils) 8.30\nCopyright (C) 2018 Free Software Foundation, Inc.\nLicense GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>.\nThis is free software: you are free to change and redistribute it.\nThere is NO WARRANTY, to the extent permitted by law.\n\nWritten by Richard M. Stallman and David MacKenzie.\n"
Process 396885 exited with status = 0 (0x00000000) 

(lldb) target create "/tmp/untitled/untitled"
Current executable set to '/tmp/untitled/untitled' (x86_64).
(lldb) r
Process 396365 launched: '/tmp/untitled/untitled' (x86_64)
Process 396365 stopped
* thread #1, name = 'untitled', stop reason = signal SIGSTOP
    frame #0: 0xffffffffffffffff 
QProcess: Destroyed while process ("/bin/ls") is still running.