Populate CodeReviewCommit before passing to MergeValidators

The onPreMerge method of MergeValidationListener may reasonably
assume that the fields of CodeReviewCommit are populated, for example
that commit.notes() will not NPE. The previous ordering of code in
MergeOp.validateChangeList() made this assumption false.

Change-Id: I9bd9e76bb09a25faf57df7080cdb0c8f878a7471
1 file changed