
`exec.CombinedOutput()` intermittently returns `ECHILD` due to our signal handling. `wait(2)`: https://man7.org/linux/man-pages/man2/wait.2.html > ECHILD (for waitpid() or waitid()) The process specified by pid > (waitpid()) or idtype and id (waitid()) does not exist or is > not a child of the calling process. (This can happen for > one's own child if the action for SIGCHLD is set to SIG_IGN. > See also the Linux Notes section about threads.) Fix #4387 Signed-off-by: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp>