The test illustrates failure in issue #5320. Here derivation and
it's built input have identical CA sotre path. As a result we generate
extraneout reference to build input:
$ make installcheck
...
ran test tests/selfref-gc.sh... [PASS]
ran test tests/ca/selfref-gc.sh... [FAIL]
...
deleting '/tmp/.../tests/ca/selfref-gc/store/iqciq1mpg5hc7p6a52fp2bjxbyc9av0v-selfref-gc'
deleting '/tmp/...tests/ca/selfref-gc/store/zh0kwpnirw3qbv6dl1ckr1y0kd5aw6ax-selfref-gc.drv'
error: executing SQLite statement
'delete from ValidPaths where path = '/tmp/.../tests/ca/selfref-gc/store/fsjq0k146r85lsh01l0icl30rnhv7z72-selfref-gc';':
constraint failed (in '/tmp/.../tests/ca/selfref-gc/var/nix/db/db.sqlite')
