[Libguestfs] [PATCH libnbd v4 0/2] copy: Use preferred block size for copying

[Richard W.M. Jones]

v3 was:
https://listman.redhat.com/archives/libguestfs/2022-June/029336.html

v4 makes almost all of the recommended changes from Laszlo's reviews.

I have dropped the third patch (the one which stablises
copy/copy-nbd-error.sh test).  That patch is still necessary, but it's
not so urgent because the null: destination no longer advertises a 4M
preferred block size, so the test fails only very rarely as before.
Also I'd like to get Eric's input on that test when he's back.

Rich.