No snapshot data when running local experiment

I have successfully built images for `quickjs`, `libarchive`, etc, and run local experiment using
```
PYTHONPATH=. python3 experiment/run_experiment.py \
--experiment-config run.config \
--benchmarks quickjs_eval-2020-01-05 libarchive_libarchive_fuzzer \
--experiment-name test--0 \
--fuzzers aflplusplus \
-mc 4 -rc 4

```
The `run.config` file:
```
# The number of trials of a fuzzer-benchmark pair.
trials: 10

# The amount of time in seconds that each trial is run for.
# 1 day = 24 * 60 * 60 = 86400
max_total_time: 600

# The location of the docker registry.
# FIXME: Support custom docker registry.
# See https://github.com/google/fuzzbench/issues/777
docker_registry: gcr.io/fuzzbench

# The local experiment folder that will store most of the experiment data.
# Please use an absolute path.
experiment_filestore: /tmp/experiment-data

# The local report folder where HTML reports and summary data will be stored.
# Please use an absolute path.
report_filestore: /tmp/report-data

# Flag that indicates this is a local experiment.
local_experiment: true
```

Then the output just repeats
```
INFO:root:Reading experiment data from db.
INFO:root:Done reading experiment data from db.
WARNING:root:No snapshot data.
INFO:root:Finding trials to schedule.
INFO:root:Starting trials.
INFO:root:Started 0 trials.
INFO:root:Reading experiment data from db.
INFO:root:Done reading experiment data from db.
WARNING:root:No snapshot data.
INFO:root:Finding trials to schedule.
INFO:root:Starting trials.
INFO:root:Started 0 trials.
INFO:root:Measuring all trials.
INFO:root:Measuring all trials.
INFO:root:Reading experiment data from db.
INFO:root:Done reading experiment data from db.
WARNING:root:No snapshot data.
```

I pressed Ctrl+C and inspected the dirs in the container, `experiment-folders`, `measurement-folders` and `reports` are all empty.

On the host, I have
```
/tmp/experiment-data/
├── local.db
├── test--0
│   ├── coverage-binaries
│   │   ├── coverage-build-libarchive_libarchive_fuzzer.tar.gz
│   │   └── coverage-build-quickjs_eval-2020-01-05.tar.gz
│   └── input
│   ├── config
│   │   └── experiment.yaml
│   └── src.tar.gz

```
However, there is nothing under `/tmp/report-data/`. I wonder where went wrong.