Comment 7 for bug 321389

These commands generate a branch viztest to show the behaviour.

The resulting graph of bzr viz of the viztest branch is:
 * Merge
 * A2
 * A1
 * B2
 * B1
 * Initial commit

While the expected result would be:
 * Merge
 * B2
 * A2
 * B1
 * A1
 * Initial commit