Missing
=======

Missing is used to find out the differences between the current branch and
another branch.

The performance analysis itself brings no further points than the
incremental-push-pull one.

More importantly, the UI have been considered not optimal: missing finds and
displays the differences between two branches, presenting the revisions that
are not common to both branches as two sets:

* the revisions that are present only in the current branch,
* the revisions that are present only in the other branch.

A quick and dirty survey indicates that most of the users are interested in
only one set of revisions at a time.

From a performance point of view, it may be more appropriate to calculate only
the set the user is asking for.

It has been proposed that the missing command be deprecated in favor of a
--dry-run option for the push, pull, merge commands.

In the mean time, the missing command stays interesting as it provides an easy
way to test, measure and optimize graph differences processing.
