Clear configured merge-base when switching upstream.

Clear configured merge-base when switching upstream.

Otherwise, the old merge-base value can confuse the hell out of `git cl upload`.

BUG=none

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=266648

[Bernhard Bauer, 2014-04-25 11:17:50]

Please review.

[Bernhard Bauer, 2014-04-28 17:14:54]

Ping? :)

[iannucci, 2014-04-28 18:55:17]

Ah good catch. I didn't remember to update git-cl-upstream :/

That said... the function which grabs the merge base should be constraining it
to be between <real_merge_base>..<branch>. Is that not happening?

(lgtm in any event)

[Bernhard Bauer, 2014-04-28 20:30:15]

On 2014/04/28 18:55:17, iannucci wrote:
> Ah good catch. I didn't remember to update git-cl-upstream :/
> 
> That said... the function which grabs the merge base should be constraining it
> to be between <real_merge_base>..<branch>. Is that not happening?

No, it only checks that the configured base is an ancestor of <branch> and not
one of the real merge base. If it's outside of the path from <real_merge_base>
to <branch> but still an ancestor of <branch>, it will accept it.

> (lgtm in any event)

[Bernhard Bauer, 2014-04-28 20:30:19]

The CQ bit was checked by bauerb@chromium.org

[commit-bot: I haz the power, 2014-04-28 20:30:33]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/bauerb@chromium.org/252683003/1

[commit-bot: I haz the power, 2014-04-28 20:32:32]

Change committed as 266648