iotests: Make _filter_nbd support more URL types
This function should support URLs of the "nbd://" format (without
swallowing the export name), and for "nbd:///" URLs it should replace
"?socket=$TEST_DIR" by "?socket=TEST_DIR" because putting the Unix
socket files into the test directory makes sense.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>