Cannot create AR archive

[davinerd]

I'm trying to create a custom deb package (ar format) and I'm receiving an error when setting the libarchive.constants.ARCHIVE_FORMAT_AR in libarchive.public.create_file.
The code is below:

import libarchive.constants
import libarchive.public

newDeb = ''.join(random.choice(string.ascii_lowercase + string.digits + string.ascii_uppercase) for _ in range(8))

tmpRan = ''.join(random.choice(string.ascii_lowercase + string.digits + string.ascii_uppercase) for _ in range(8))
tmpDir = '/tmp/' + tmpRan

newDeb = newDeb + ".deb"

for entry in libarchive.public.create_file('/tmp/'+newDeb,
                libarchive.constants.ARCHIVE_FORMAT_AR,
                [tmpDir+'/debian-binary', tmpDir+'/control.tar.gz', tmpDir+'/data.tar.gz' ]):
                print(entry)

the error is:

Traceback (most recent call last):
  File "test.py", line 429, in ar_files
    [tmpDir+'/debian-binary', tmpDir+'/control.tar.gz', tmpDir+'/data.tar.gz' ]):
  File "/usr/local/lib/python2.7/dist-packages/libarchive/adapters/archive_write.py", line 199, in _create
    _set_write_context(a, format_code, filter_code)
  File "/usr/local/lib/python2.7/dist-packages/libarchive/adapters/archive_write.py", line 184, in _set_write_context
    format_code)
  File "/usr/local/lib/python2.7/dist-packages/libarchive/adapters/archive_write_set_format.py", line 8, in archive_write_set_format
    code)
  File "/usr/local/lib/python2.7/dist-packages/libarchive/calls/archive_write_set_format.py", line 8, in _check_zero_success
    raise ValueError("Function returned failure: (%d)" % (value))
ValueError: Function returned failure: (-30)

If I change the format to libarchive.constants.ARCHIVE_FORMAT_7ZIP, everything goes well and it creates the archive.
Here are some info on my env:

root@ubuntu:/tmp# pip list | grep libarchive
libarchive (0.4.3)
root@ubuntu:/tmp# lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu 14.04.2 LTS
Release:    14.04
Codename:   trusty
root@ubuntu:/tmp# python -V
Python 2.7.6
root@ubuntu:/tmp#