Fix error reporting after ioctl() call with pg_upgrade --clone
errno was not reported correctly after attempting to clone a file,
leading to incorrect error reports. While scanning through the code, I
have not noticed any similar mistakes.
Error introduced in
3a769d8.
Author: Justin Pryzby
Discussion: https://postgr.es/m/
20220731134135.GY15006@telsasoft.com
Backpatch-through: 12