I've just hit a bug in the build system on OS X Mavericks that looks to be due to an update of XCode 6.1. The bug is causing the build process for Python via Homebrew to fail. This is a known issue - apparently XCode 6.1 always favors the OS X 10.10 SDK, even on OS X 10.9.

https://github.com/Homebrew/homebrew/issues/33431

Hopefully this issue is resolved soon. Until then, if you run into this problem, you have two choices:

- Upgrade to OS X Yosemite (available free on the App Store)

- Download XCode 6.01 from the Apple Developer Site:  https://developer.apple.com/xcode/downloads/