uv

dd760ee5 - Normalize `platform_system` to `sys_platform` (#9949)

Normalize `platform_system` to `sys_platform` (#9949) ## Summary A revival of an old idea (#9344) that I have slightly more confidence in now. I abandoned this idea because (1) it couldn't capture that, e.g., `platform_system == 'Windows' and sys_platform == 'foo'` (or some other unknown value) are disjoint, and (2) I thought that Android returned `"android"` for one of `sys_platform` or `platform_system`, which would've made this logic incorrect. However, it looks like Android... doesn't do that? And the values here are almost always in a small, known set. So in the end, the tradeoffs here actually seem pretty good. Vis-a-vis our current solution, this can (e.g.) _simplify out_ expressions like `sys_platform == 'win32' or platform_system == 'Windows'`.