Unlike `waitpid`, `virProcessWait` only returns -1 (error) or 0
(success), so comparing that to `pid` will always be false and the
parent will report failure with:

error : main:851 : Failed to fork as daemon: No such file or directory

even though the grandchild process is succesfully running. Note that the errno message is misleading: it was last set when trying to find a restart state file.