* Updates bob-builder to a version that clears out the previous
build directory, which prevents the stale files seen in #379.
* Adds a `buildenv-heroku-16` Make command to simplify the
building and use of the Heroku-16 binary build environment.
* Sets `S3_BUCKET` and `S3_PREFIX` in the Docker image, to save
having to do so manually each time.
* Removes the duplication of the bob-builder dependency between
`Dockerfile` and `requirements.txt`.
* Disables the pip version check during Docker build, to avoid the
noisy stderr warning about Ubuntu 16.04 pip being older (v8.1.1).
* Adds a `.dockerignore` to speed up the Docker build, by reducing
the build context transferred to the daemon from 60MB to 2MB.
* Applies some Dockerfile best practices like disabling/removing
cached files (since layer invalidation makes caching pointless).
In cases where there is no stderr there was previously no output,
which made it hard to find the cause. The assertion messages have
also been adjusted to remove the repetition (shunit2 already outputs
expected vs actual itself).
Before:
```
testPipenv
ASSERT:Expected captured exit code to be 0; was <2> expected:<0> but was:<2>
testPipenvVersion
```
After:
```
testPipenv
ASSERT:Captured exit code - expected:<0> but was:<2>
! Warning: Your application is missing a Procfile. This file tells Heroku how to run your application.
! Learn more: https://devcenter.heroku.com/articles/procfile
-----> Installing python-2.7.13
-----> Installing pip
-----> Generating 'requirements.txt' with pipenv
testPipenvVersion
```
Fixes#389.
So that any changes made to `.heroku/` within pre_compile (such as
installing additional libraries required for the later pip install) are
not clobbered by the cache being copied over afterwards.
Fixes#320.
* update python.gunicorn.sh to WEB_CONCURRENCY.sh
* don't remove WEB_CONCURRENCY for prefixed 0s
* split gunicorn functionality into its own file
* cleanup comments
* fix var ordering
* add retry to curl
* use proper url for buildpack stdlib
kennethreitz
David Lord