I belive there is a problem with Twitter OAuth Authentication in
combination with the force_login=true parameter

The issue occurs only when I am logged in to twitter.com with one user and
I need to use OAuth Authentiation and force_login=true against another user.

The applications that I can replicate this problem in are: 
http://twitter.com/oauth_clients/details/1827
http://twitter.com/oauth_clients/details/2475

These two applications are hosted on the Google App Engine, created in
Python using TwitterOAuthClient.py package on GoogleCode.  I don't belive
it is a platform issue.

Steps to reproduce:

Pre-req
You must have two accounts on twitter: UserA and UserB

1. Login to the Twitter site with a user account (UserA)
2. Go to an application that uses Twitter OAuth authentication and
force_login=true OAuth url.
3. Attempt to login to the site
3a. The site will get a request token and direct you to the appropriate
authentication url
(http://twitter.com/oauth/authenticate?force_login=true&oauth_token=[[REQUESTTOKEN]])
4. Twitter presents a page requesting that the username and password.
5. Login with UserB's credentials
6. You will be redirected to the application's site
6a. The application will parse the token, request an access token.

It appears that the twitter.com site at step 5 is assigning the request
token to UserA and not the authenticating UserB, so when steps 5a obtains
an access_token it is infact obtaining the token for UserA.

7. A request to verify_credentials.json will show that the tokens are
assigned to UserA's credentials and not UserB.