XCode Command Line Tools 15.0 was recently released, and it contains a
broken version of ncurses 6.0. Some uses of Python's `curses` module
will segfault when compiled with it. The solution is to switch to using
the version of ncurses from Homebrew, which is currently 6.4. Support
for ncurses 6 was added to Python 3.7 and was backported to 3.6 and 2.7,
so this change should not break any recently supported Python versions.
Tested with Python 3.12, 3.11, and 2.7, and all tests in
the `test.test_curses` module pass without issue.
See https://github.com/python/cpython/issues/109617 and
https://github.com/python/cpython/issues/69906 for more information.
The -s flag assures that nothing can be installed to user site-packages
but doesn't keep ensurepip from looking there for Pip.
If Pip is installed in the user site-packages directory, pip won't be installed
for the newly built python -- and its shim won't be created.
-I makes the build install Pip in any case.
The user site-packages installation will override it --
but we'll have the shim at least.
This is needed to find other Python deps (e.g. libintl) in Homebrew if it has
nonstandard prefix (e.g. in Apple M1)
* Re-allow to search Homebrew for zlib everywhere