Repair -full sets "repairedAt" value

src/java/org/apache/cassandra/service/ActiveRepairService.java:

* we only want to set repairedAt for incremental repairs including all replicas for a token range. For non-global
* incremental repairs, forced incremental repairs, and full repairs, the UNREPAIRED_SSTABLE value will prevent
* sstables from being promoted to repaired or preserve the repairedAt/pendingRepair values, respectively.

$ for f in *Data.db; do echo $f; sudo /usr/bin/sstablemetadata $f |grep -i repaired; done
md-10-big-Data.db
Repaired at: 0
md-5-big-Data.db
Repaired at: 0
md-6-big-Data.db
Repaired at: 0
md-7-big-Data.db
Repaired at: 0
md-8-big-Data.db
Repaired at: 0
md-9-big-Data.db
Repaired at: 0

$ nodetool repair -full 
[2020-01-17 00:25:35,192] Starting repair command #1 (e0edeee0-38bf-11ea-b3f5-891068749d18), repairing keyspace ext_alt_live with repair options (parallelism: parallel, primary range: false, incremental: false, job threads: 1, ColumnFamilies: [], dataCenters: [], hosts: [], # of ranges: 3, pull repair: false)
[2020-01-17 00:27:51,874] Repair session e1930880-38bf-11ea-b3f5-891068749d18 for range [(3074457345618258602,-9223372036854775808], (-9223372036854775808,-3074457345618258603], (-3074457345618258603,3074457345618258602]] finished (progress: 71%)
[2020-01-17 00:27:51,920] Repair completed successfully
[2020-01-17 00:27:51,925] Repair command #1 finished in 2 minutes 16 seconds
[2020-01-17 00:27:51,980] Replication factor is 1. No repair is needed for keyspace 'system_auth'
[2020-01-17 00:27:52,003] Starting repair command #2 (327adb10-38c0-11ea-b3f5-891068749d18), repairing keyspace system_traces with repair options (parallelism: parallel, primary range: false, incremental: false, job threads: 1, ColumnFamilies: [], dataCenters: [], hosts: [], # of ranges: 2, pull repair: false)
[2020-01-17 00:27:52,052] Repair session 327d4c10-38c0-11ea-b3f5-891068749d18 for range [(3074457345618258602,-9223372036854775808]] finished (progress: 83%)
[2020-01-17 00:27:52,081] Repair session 327dc140-38c0-11ea-b3f5-891068749d18 for range [(-3074457345618258603,3074457345618258602]] finished (progress: 100%)
[2020-01-17 00:27:52,086] Repair completed successfully
[2020-01-17 00:27:52,090] Repair command #2 finished in 0 seconds

$ for f in *Data.db; do echo $f; sudo /usr/bin/sstablemetadata $f |grep -i repaired; done
md-11-big-Data.db
Repaired at: 0
md-12-big-Data.db
Repaired at: 0
md-13-big-Data.db
Repaired at: 1579220735212
md-14-big-Data.db
Repaired at: 1579220735212
md-15-big-Data.db
Repaired at: 1579220735212
md-16-big-Data.db
Repaired at: 1579220735212