Previously, when deleting a symlink that points to an xLO, we'd clean
up the xLO's segments then delete the symlink, leaving the xLO itself
busted.
Similar trouble would come from overwriting a symlink pointing to an
xLO. Check for a Content-Location in the HEAD response and leave such
segments.
Co-Authored-By: Clay Gerrard <clay.gerrard@gmail.com>
Change-Id: I45b210cf380a68bd88187c91fa2d63a8b2bb709b