Preserve API errors thrown by metadata import failure.
Preserve API errors thrown by metadata import failure.

Signed-off-by: John Else <37b74501daa612e48fea94f9846ed4ddeb6a8f07@citrix.com>

koushikcgit/xcp-rrdd,robhoes/squeezed,koushikcgit/xcp-networkd,johnelse/xcp-rrdd,djs55/xcp-networkd,sharady/xcp-networkd,sharady/xcp-networkd,koushikcgit/xcp-rrdd,djs55/xcp-networkd,simonjbeaumont/xcp-rrdd,djs55/xcp-rrdd,koushikcgit/xcp-networkd,koushikcgit/xcp-rrdd,simonjbeaumont/xcp-rrdd,johnelse/xcp-rrdd,djs55/xcp-rrdd,djs55/squeezed