Please install MacVim using this command:
brew install macvim --env-std --override-system-vim
Then install Powerline locally with pip install --user, or by running these commands in the powerline directory:
./setup.py build
./setup.py install --user
This is caused by an invalid sys.path when using system vim and system Python. Please try to select another Python distribution:
sudo port select python python27-apple
See issue #39 for a discussion and other possible solutions for this issue.
This is a known libuv issue that happens if one is trying to watch too many files. It should be fixed in libuv-0.12. Until then it is suggested to either disable status_colors (from powerline.segments.common.vcs.branch()) or choose stat-based watcher (will have effectively the same effect as disabling status_colors).