Fix changeset_is_pending() to not throw an error if the changeset is empty.
Review Request #2846 — Created Feb. 9, 2012 and submitted
Fix changeset_is_pending() to not throw an error if the changeset is empty. Our existing code to fetch the changeset would throw EmptyChangesetError for any operations, but this didn't entirely make sense for empty changesets. This is especially bad in environments where people pull files in and out of changesets.
Ran unit tests.
