qemu-img: Ignore Error objects where the return value suffices

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <20200707160613.848843-44-armbru@redhat.com>
[One more in img_amend() due to commit 0bc2a50e17 "qemu-option: Use
returned bool to check for failure"]
1 file changed