Missing import in openid.extension

[kilink]

This seemed too lightweight of an issue for a pull request, but the toMessage method of openid.extension.Extension references the warnings module without it having been imported.

Test case:

import openid.extension

ext = openid.extension.Extension()
ext.toMessage()

Even though this use of the method is deprecated, I consider it a bug.

[willnorris]

no change is too small for a pull request :)

[timcappalli]

This repo is being archived. Closing issue.