I find it really attractive when a girl has strong political views that she is not afraid to defend. If a girl seems indifferent about politics it comes across as really ignorant.
I only find it unattractive when girls feel so strongly that they can't keep their cool during a reasonable debate - that comes across as a little obnoxious - and when don't debate well lol. I remember debating with this girl I use to be into about whether or not you could be racist to a white person. She seemed insistent that racism required power, which white people have, which was a fair argument, but she got really angry. She seemed to miss that the only difference in our beliefs was not on the place of different races within our society, but how we defined the word. Things like this turned me off her in the end.
But overall, I would consider it a massive turn off if a girl didn't consider herself a feminist, or didn't have a view on who should win the next election etc.
I guess I might also be turned off by a girl's political views - ie being a tory.