backup: restore: process files until EOF received
backup: restore: process files until EOF received

Not only until unpacker process is running. This is another race
condition, which would cause some data left in the pipe buffer not
processed.

marmarek/qubes-core-admin,woju/qubes-core-admin,woju/qubes-core-admin,QubesOS/qubes-core-admin,QubesOS/qubes-core-admin,marmarek/qubes-core-admin,woju/qubes-core-admin,woju/qubes-core-admin,marmarek/qubes-core-admin,QubesOS/qubes-core-admin