Issue #19340: Fix test_sysconfig when Python is built with an empty prefix.
Patch by Sunny K.
Issue #19352: Fix unittest discovery when a module can be reached through several paths (e.g. under Debian/Ubuntu with virtualenv).
Issue #19356: Avoid using a C variabled named "_self", it's a reserved word in some C compilers.
Issue #19360: fix test_site when Python is installed into $HOME/.local
Increase the coverage of macurl2path. Patch by Colin Williams.