v266

• Added a warning when the files for multiple package managers are found. In the future this warning will become an error. (#1692)
• Updated the build log message shown when installing dependencies to include the package manager command being run. (#1689)
• Changed test dependency installation on Heroku CI to now install requirements.txt and requirements-test.txt in a single pip install invocation rather than separately. This allows pip's resolver to resolve any version conflicts between the two files. (#1689)
• Improved the error messages and buildpack metrics for package manager related failures. (#1689)
• Improved the build log output, error messages and buildpack failure metrics for the NLTK downloader feature. (#1690)