qemu: Improve error reporting when migration can't connect
Tested with upstream qemu as of Jun 3 2010
If the source qemu instance can't connect to the migration destination (say
there is no listening QEMU instance, or port is blocked by a firewall), all we
get is info migrate -> Migration status: failed. This is all we have to report
back to libvirt users if their firewall is misconfigured, which is crappy.
Ideally, if we can't connect, migration would fail immediately with a relevant
message and strerror(). More info from 'info migrate' would be nice too, no
idea how this will play with QMP though.
As a slightly related issue, try entering
We get a 'migration failed' error, and then the monitor hangs!