Error in retrieval of commit data and most recent tag

There isn't enough information here to reproduce. Please include reproduction instructions.

It's actually quite obvious. In packaging._get_revno_and_last_tag we have following code:

changelog = git._iter_log_oneline(git_dir=git_dir)
row_count = 0
for row_count, (ignored, tag_set, ignored) in enumerate(changelog):

If git._iter_log_online returns None what it sometimes does, we get "TypeError: 'NoneType' object is not iterable".
You can also achieve this by setting os.environ['SKIP_WRITE_GIT_CHANGELOG'] = '1' in your setup.py.
I'll attach a small sample project that does exactly this.
The fix is just to add the line changelog = changelog if changelog else [] after changelog = git._iter_log_oneline(git_dir=git_dir). I have a PR ready. Just let me know.

I added a PR under https://review.openstack.org/#/c/194954/

Change abandoned by Florian Wilhelm (<email address hidden>) on branch: master
Review: https://review.openstack.org/197508
Reason: This was just a duplicate of https://review.openstack.org/#/c/194954/

Reviewed: https://review.openstack.org/194954
Committed: https://git.openstack.org/cgit/openstack-dev/pbr/commit/?id=c3fc63c64f9db3b98d16fa77a8021b3f5d5b34a4
Submitter: Jenkins
Branch: master

commit c3fc63c64f9db3b98d16fa77a8021b3f5d5b34a4
Author: Florian Wilhelm <email address hidden>
Date: Fri Jun 19 12:01:12 2015 +0200

    Fix retrieval of commit data and most recent tag.

    git._iter_log_online() returns None in some cases for instance
    when SKIP_WRITE_GIT_CHANGELOG is set to true. This is fixed by
    returning an empty list in _iter_log_online.

    Also the check if a changelog based on git should be written
    was moved from git._iter_log_online to git.write_git_changelog
    which makes more sense since some functions were calling
    git._iter_log_online to get the changelog for other reasons than
    writing it.

    Additionally a unittest was added to check that setting the
    environment variable SKIP_WRITE_GIT_CHANGELOG to true does not
    break anything when retrieving the git version.

    Change-Id: Ib12df23ab25b290dd394f9cb1456b8d5da57306a
    Closes-Bug: 1467440