David Zülke

@stesie can you please allow public listing on that bucket? You can now (see develop branch and 30f97f8) also use `UPSTREAM_S3_BUCKET` and `UPSTREAM_S3_PREFIX`, then you don't have to worry about...

Is it not enough that the level 2 optimizations can be enabled in the `config` section of `composer.json`?

What do you think a good flag would be? I am a little wary of a blanket `COMPOSER_INSTALL_ARGS` or something, as people will inevitably do wild stuff with it...

What if we made the Heroku global config default to true for both level 1 (https://getcomposer.org/doc/articles/autoloader-optimization.md#optimization-level-1-class-map-generation) and level 2A (https://getcomposer.org/doc/articles/autoloader-optimization.md#optimization-level-2-a-authoritative-class-maps), and if users have specific code that breaks with that,...

Can you help me understand levels 2/A and 2/B, @stof... the docs say they're mutually exclusive, but looking at the code, it appears you can enable both at the same...

That cache directory isn't created by the PHP buildpack, but by the addition of your list-app-dir buildpack ;) When the build system sources `export` before running your buildpack, this also...