Pyenv

* python-build: Add CPython 2.7.15
* python-build: Add PyPy 6.0.0
* python-build: Allow overriding HTTP client type based on environment variable `PYTHON_BUILD_HTTP_CLIENT` (1126)
* python-build: Use version-specific `get-pip.py` when installing 2.6 and 3.2 (1131)
* pyenv: Merge rbenv master (1151)
* pyenv: Make `pyenv-rehash` safer for multiple processes (1092)

* python-build: Add CPython 3.6.5
* python-build: Set openssl PKG_CONFIG_PATH for python 3.7 (1117)
* python-build: Add ActivePython versions 2.7.14, 3.5.4, 3.6.0 (1113)
* python-build: Unset `PIP_VERSION` before invoking `get-pip.py` as a workaround for `invalid truth value` error (1124)

* python-build: Add PyPy3 5.10.1 (1084)
* python-build: Add CPython 3.5.5 (1090)
* python-build: Add Anaconda[23]-5.1.0 (1100)
* python-build: Fix checksum issue for CPython 3.4.8 (1094)
* python-build: Prevent Anaconda from installing a `clear` shim (1084)

* python-build: Add CPython 3.6.4
* python-build: Add PyPy[23] 5.10

* python-build: Import changes from ruby-build v20171031 (1026)
* python-build: Ignore LibreSSL bundled with macOS 10.13 (1025)
* python-build: Skip passing `--enable-unicode` to CPython 3.3+ (912)
* python-build: Add CPython 3.3.7 (1053)
* python-build: Add micropython 1.9.3
* python-build: Add PyPy 5.9.0
* python-build: Add Miniconda[23] 4.3.14, 4.3.21, 4.3.27, 4.3.30
* python-build: Add Anaconda[23] 5.0.1
* python-build: Update Anaconda[23] 5.0.0 to 5.0.0.1 bugfix release

* python-build: Add CPython 3.6.3
* python-build: Add CPython 3.7.0a1
* python-build: Add Anaconda[23] 5.0.0