Removed second fetch

The logic here I think was meant to have the PB client behavior match the HTTP
client behavior when only fetching the meta and siblings were found to
be present. With HTTP this is required because of how the API works (each sibling needs to be fetched to get the metadata) 

This isn't necessary with PB; the initial fetch returns all metadata if there's siblings. This also fixes the actual bug where a there was a missing conditional that checked to see if the first fetch was done with headOnly() causing any fetch that had siblings to be done twice. 

Fixes #192