Conjoined items do not display unless there are two or more in a set

* Evergreen master / 3.0 / 2.12

Even though this sounds like #1703678 "Conjoined items do not display without an extra copy attached to the record", it is different.

Test case:

1. Add a single record (say ID 1234) as a peer to another record (say ID 1000).
2. Display record 1234. It will show that record 1000 is the set to which it belongs under the "foreign item" heading below the normal copy display.
3. Display record 1000. Under the normal copy display, it will not show that it contains a foreign item.

This is the result of an off-by-one error in the copy_table.tt2 template; to fix it, we change:

[%- IF copy_info.peer_bib_marc.size > 1;

to:

[%- IF copy_info.peer_bib_marc.size > 0;

Once the fix is in place, record 1000 will link to record 1234 in the list of set items.