Cache reused values in autoCloseChanges

The tip commit and branch key are passed into the submodule update
helper. Hold them in varibles for reuse, to reduce redundant code.

It is not necessary to reset the RevWalk. The submodule updater is
only using the revision pool to parse commits. It doesn't perform a
traversal, so the reset is merely wasting CPU cycles here.

Change-Id: Id6545033291539b862291eb88d6e8e85a24cb34c
1 file changed