ClearCase and VersionVault can track symbolic links, which don't seem to show up as elements of their own, but do show up in directory diffs. The way these were represented (as `filename1 -> filename2`) was then crashing when trying to query the OID. This change wraps that section of our directory processing in a try/except, so we can log the error and continue on. The result of this is that changes which include added or deleted symlinks will post without errors. The resulting diff will show the added line in the directory listing. Testing Done: Posted activity changes which involved symbolic links. Saw the expected diffs instead of having `rbt post` crash.