Add strace hack for tarfile test

[zooba]

This should never be merged. I'm trying to collect more info about a test failure.

[tirkarthi]

cc : @vstinner @pablogsal since they look after buildbots and pipelines with this being a failure in Ubuntu builds in Azure pipelines.

[zooba]

If you look on the summary page of the Pipelines build, there'll be a build artifact available that (hopefully) will include the strace log:

Right now it has an error that I think means I needed "sudo strace", so trying that now.

[zooba]

Here is the output of strace for test_tarfile (including a time.sleep at the start, and a time.sleep/os.kill at the end):

strace: Process 5154 attached
select(0, NULL, NULL, NULL, {1, 828371}) = 0 (Timeout)
umask(022)                              = 022
open("/home/vsts/work/1/s/build/test_python_5154/@test_5154_tmp-tardir/tmp.tar", O_WRONLY|O_CREAT|O_TRUNC|O_CLOEXEC, 0666) = 3
write(3, "BZh91AY&SYY{\270\344\0\0\24P\0\300\0\4\0\0\10 \0000\314\5)\246"..., 46) = 46
close(3)                                = 0
stat("/home/vsts/work/1/s/build/test_python_5154/@test_5154_tmp-tardir/tmp.tar", {st_mode=S_IFREG|0666, st_size=46, ...}) = 0
umask(022)                              = 022
select(0, NULL, NULL, NULL, {5, 0})     = 0 (Timeout)
kill(5154, SIGKILL <unfinished ...>
+++ killed by SIGKILL +++

As near as I can tell, nothing unexpected here? @njsmith any ideas?

[zooba]

This is the output of checking ACLs on the sources directory (which is where temp files get put for these tests):

Default mount options:    user_xattr acl
/dev/sda1 on / type ext4 (rw,relatime,discard,data=ordered)
# file: .
# owner: vsts
# group: docker
user::rwx
user:vsts:rwx
group::rwx
mask::rwx
other::rwx
default:user::rwx
default:user:vsts:rwx
default:group::rwx
default:mask::rwx
default:other::rwx