[PATCH 3 of 4] tests: merge 'test-push-validation.t' into 'test-push.t'

[timeless]

Pierre-Yves David wrote:
> tests: merge 'test-push-validation.t' into 'test-push.t'
>
> That test file is very small and is merge with the new 'test-push.t'. No logic
> is changed but repository name are update to avoid collision.
>
> We don't register this as a copy because is actually a "ypoc" merging two file
> together without replacing the destination and Mercurial cannot express that.

Actually, it can:

0: a b
0->1: rename a->d
0->2: rename b->d
1+2->3: merge d

This should give you the history you want in `hg ann`.