I've written a PEP proposing a small enhancement to the Python loop control statements. Short version: here's what feels to me like a Pythonic way to spell "repeat until":
while: <do stuff> break if <done condition>
The PEP goes into some detail on why this feels like a readability improvement in the more general case, with examples taken from the standard library:
Unlike Larry, I don't have a prototype, and in fact if this idea meets with approval I'll be looking for a volunteer to do the actual implementation.
PS: this came to me in a dream on Sunday night, and the more I explored the idea the better I liked it. I have no idea what I was dreaming about that resulted in this being the thing left in my mind when I woke up :)