Hi Daniel,
I'm a relative novice at Galaxy administration, but at first blush it looks like you're missing (or the Galaxy user doesn't have permissions on) the paste process. You can try a GIT status or diff to see if something just didn't download right. Otherwise, check to make sure that your entire galaxy install directory is owned by the Galaxy user and the group that the Galaxy user belongs to.
Hope this helps!
pkg_resources.DistributionNotFound: Paste
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