Add integration tests to check that only the given path is transferred

Until recently (it was fixed in ac2999a2) when a path was transferred
other shares with the target user were removed, so a test was added to
ensure that it does not happen again.

Besides that a test to ensure that other files with the target user are
not transferred was added too (it did not fail before, but seemed
convenient to have that covered too :-) ).

Signed-off-by: Daniel Calviño Sánchez <danxuliu@gmail.com>