Pushed some coverage in in "overwrite" mode, saw this in the database:
```
mysql> select * from repository_coverage;
+----+----------+----------+--------+-----------------------------+
| id | branchID | commitID | pathID | coverage |
+----+----------+----------+--------+-----------------------------+
| 4 | 1 | 82639 | 0 | D |
| 7 | 2 | 116868 | 173 | CCCUUU |
| 8 | 2 | 116868 | 12384 | CUCUCU |
| 9 | 2 | 116868 | 172 | +J{"U":6,"C":6,"N":0,"X":0} |
| 10 | 2 | 116868 | 145 | +J{"U":6,"C":6,"N":0,"X":0} |
+----+----------+----------+--------+-----------------------------+
5 rows in set (0.01 sec)
```
Then pushed some coverage in in "update" mode, saw this in the database:
```
mysql> select * from repository_coverage;
+----+----------+----------+--------+-----------------------------+
| id | branchID | commitID | pathID | coverage |
+----+----------+----------+--------+-----------------------------+
| 4 | 1 | 82639 | 0 | D |
| 7 | 2 | 116868 | 173 | CCCCUU |
| 8 | 2 | 116868 | 12384 | CUCUCU |
| 9 | 2 | 116868 | 172 | +J{"U":5,"C":7,"N":0,"X":0} |
| 10 | 2 | 116868 | 145 | +J{"U":5,"C":7,"N":0,"X":0} |
+----+----------+----------+--------+-----------------------------+
5 rows in set (0.00 sec)
```
Note that the update (changing one "U" to a "C") properly updated the aggregate rows.