This broke the bazel build of inception/download_and_preprocess_flowers
The way that this script is written doesn't actually allow it to be ran
outside bazel, some refactoring would be needed if you want to run it
standalone.

It should be ran using

```
bazel build inception/download_and_preprocess_flowers

bazel-bin/inception/download_and_preprocess_flowers
"${FLOWERS_DATA_DIR}"
```