Comment 8 for bug 1781169

Same with 1.2.29 from xenial:

open("/var/lib/dpkg/lock-frontend", O_RDWR|O_CREAT|O_NOFOLLOW, 0640) = 4
fcntl(4, F_SETFD, FD_CLOEXEC) = 0
fcntl(4, F_SETLK, {l_type=F_WRLCK, l_whence=SEEK_SET, l_start=0, l_len=0}) = 0
open("/var/lib/dpkg/lock", O_RDWR|O_CREAT|O_NOFOLLOW, 0640) = 5
fcntl(5, F_SETFD, FD_CLOEXEC) = 0
fcntl(5, F_SETLK, {l_type=F_WRLCK, l_whence=SEEK_SET, l_start=0, l_len=0}) = 0
[...] reading files ]
close(5) = 0
fcntl(5, F_SETFD, FD_CLOEXEC) = 0
fcntl(37, F_SETFD, FD_CLOEXEC) = 0
close(5) = 0
fcntl(37, F_GETFL) = 0x1 (flags O_WRONLY)
close(37) = 0
--- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=3741, si_uid=0, si_status=0, si_utime=0, si_stime=0} ---
[ reading files and writing extended_states stuff; no close(4) ]
close(4) = 0
close(5) = -1 EBADF (Bad file descriptor)
close(3) = 0
+++ exited with 0 +++