Code review comment for lp:~salgado/launchpad/bug-556594

r10632 fixes the actual bug.

When logging in with an mail address that's associated with a different
OpenID identifier, change the identifier associated with the registered
email address to match the one given by the OP. (Fixes bug 556594)

Part of the changes on this branch have already been reviewed
by Brad, so I'm including the incremental diff here: http://paste.ubuntu.com/410236/