Failing test and fix for running take_over twice.

[zbynekwinkler]

When user manages to run take_over twice with the same arguments,
tak_over creates an orphan. Fixes #617.

Update: Ready to review & merge. Required database update is included in branch.sql (deleting the orphans).

[zbynekwinkler]

We have this code in take_over:

if we_already_have_that_kind_of_account:
    new_stub_username = reserve_a_random_username(cursor)
    cursor.run( "UPDATE elsewhere SET participant=%s "
                "WHERE platform=%s AND participant=%s"
                , (new_stub_username, platform, self.username)
                )
cursor.run( "UPDATE elsewhere SET participant=%s "
            "WHERE platform=%s AND user_id=%s"
            , (self.username, platform, user_id)
            )

If we are running the second time with the same parameters the first condition is true. We are also working with only one account elsewhere so the one we are moving away and the 'new' one is the same account. Thus orphan is created.

[seanlinsley]

This seems to make sense to me. Is this ready to merge @zwn?

[zbynekwinkler]

Yes, but I'd like @whit537 to see too before we merge it since he is the only one who groks further connections within this code.

[zbynekwinkler]

@whit537 Soon we are going to assume that you have seen this and since you are not commenting it is fine for @seanlinsley to merge and for me to deploy 😉

[zbynekwinkler]

Will deploy tonight, Central European Time.

[chadwhitacre]

I reviewed this before deploying earlier today. !m @zwn