Error in EVF files parsing when start and stop time are the same

When two blocks are consecutive in a EVF file, the EvfEventsFile parser don't properly assign the first end time to the correct blocks.

Set to reproduce:

2000-01-01T00:00:00  ABC_START   (COUNT=1)
2000-01-02T00:00:00  ABC_END     (COUNT=1)
2000-01-02T00:00:00  ABC_START   (COUNT=2)
2000-01-03T00:00:00  ABC_END     (COUNT=2)
2000-01-03T00:00:00  ABC_START   (COUNT=3)
2000-01-04T00:00:00  ABC_END     (COUNT=3)

>>> EvfEventsFile('abc.evf')

| event | # | t_start    | t_stop |
|-------|---|------------|--------|
| ABC   | 3 | 2000-01-01 | NaT    |

>>> EvfEventsFile('abc.evf')['ABC']

| name | t_start | t_end               |                     |
|------|---------|---------------------|---------------------|
| 0    | ABC     | 2000-01-01T00:00:00 | NaT                 |
| 1    | ABC     | 2000-01-02T00:00:00 | 2000-01-02T00:00:00 |
| 2    | ABC     | 2000-01-03T00:00:00 | 2000-01-04T00:00:00 |