[test/pairtree,bugfix][xs]: update claim_a_bucket to claim_bucket in pairtree test (BenO made this change to pairtree in cset:190083a06386 but did not update tests ...).
[test/pairtree,bugfix][xs]: update claim_a_bucket to claim_bucket in pairtree test (BenO made this change to pairtree in cset:190083a06386 but did not update tests ...).

okfn/ofs