The mergeability flag of a change is immediately updated when the
change is created or when a new patch set is uploaded.
When a branch is updated the mergeability flag is asynchronously
updated for all open changes that are destined for that branch.
This way the mergeability flag is always up to date. With this the
(new) change screen doesn't need to explicitly trigger the update of
this flag whenever the screen is loaded. The corresponding call is
removed.
In a follow-up change we can now display the mergeability flag also in
the change tables and user dashboards which wouldn't make sense if the
displayed information is outdated.
It is important to update the mergeability flag on a branch update in
the background since the computation and even the check whether the
mergeability flag needs to be recomputed is expensive.
Change-Id: Id20e567e5c5d5b3d851ca5cda9bde01ac01c9967
Signed-off-by: Edwin Kempin <edwin.kempin@sap.com>