Coverity reported copy-paste error in WiredTiger error message

*** CID 1400492:  Incorrect expression  (COPY_PASTE_ERROR)

/src/txn/txn_timestamp.c: 650 in __wt_txn_set_commit_timestamp()

644                                 ts_string[0], ts_string[1]);

645                     }

646     

647                     if (has_stable_ts && commit_ts < stable_ts) {

648                             __wt_timestamp_to_string(commit_ts, ts_string[0]);

649                             __wt_timestamp_to_string(

>>>     CID 1400492:  Incorrect expression  (COPY_PASTE_ERROR)

>>>     "oldest_ts" in "__wt_timestamp_to_string(oldest_ts, ts_string[1])" looks like a copy-paste error.

650                                 oldest_ts, ts_string[1]);

651                             WT_RET_MSG(session, EINVAL,

652                                 "commit timestamp %s is less than the stable "

653                                 "timestamp %s",

654                                 ts_string[0], ts_string[1]);

655                     }

*** CID 1400493:  Incorrect expression  (COPY_PASTE_ERROR)

/src/txn/txn_timestamp.c: 749 in __wt_txn_set_durable_timestamp()

743                         "durable timestamp %s is less than the oldest timestamp %s",

744                         ts_string[0], ts_string[1]);

745             }

746     

747             if (has_stable_ts && durable_ts < stable_ts) {

748                     __wt_timestamp_to_string(durable_ts, ts_string[0]);

>>>     CID 1400493:  Incorrect expression  (COPY_PASTE_ERROR)

>>>     "oldest_ts" in "__wt_timestamp_to_string(oldest_ts, ts_string[1])" looks like a copy-paste error.

749                     __wt_timestamp_to_string(oldest_ts, ts_string[1]);

750                     WT_RET_MSG(session, EINVAL,

751                         "durable timestamp %s is less than the stable timestamp %s",

752                         ts_string[0], ts_string[1]);

753             }