[core] Bug Fix for JPEG service.
[core] Bug Fix for JPEG service.

neurodata/ndstore,openconnectome/open-connectome,openconnectome/open-connectome,openconnectome/open-connectome,neurodata/ndstore,openconnectome/open-connectome,neurodata/ndstore,openconnectome/open-connectome,openconnectome/open-connectome,neurodata/ndstore