git-svn commit count vs- revision count

Hi!

I've `git-svn clone`ed a pretty large repository, which took about 3 days
even with with local access to the SVN repository. To check that
everything went ok, I listed the root commits with `git fsck --root
--full` and verfied, that these are indeed root commits with no branch point.

So far so good... what's puzzling me is, that `git rev-list --all | wc -l`
says I have 40731 commits, but the SVN repository only has 21875 revisons.

Shouldn't these numbers be the same? The only explanation I have, is, that
git-svn imported one or more branches or tags, where it failed to find the
correct branch point in the history. Is there a way to figure out, if
there went something wrong and possibly fix it?

Thx,

Tobias