Possible fix for CommitBuild

Work around CommitBuild commiting dirty trees by doing a fresh write out to commit, instead of committing a previously-written and possibly dirty tree.

It comes with a performance penalty, and you /may/ wish to add a switch that switches between "just use the existing tree, though it might be dirty" and "write out fresh", because if they have a plugin combination that doesn't yield a dirty tree, the overhead of the additonal writeout would be undesirable.