Helm releasesync does git pull after having computed changes, but before applying them

[ncabatoff]

I noticed while working on #1089 that the 'git pull' is done after having examined the repo and compared it to the cluster to determine what changes to make. So we figure out what to do, then git pull, then apply changes based on a potentially stale plan. Looks like a bug to me. See releasesync.ReleaseChangeSync.sync() for the pull in question.

[squaremo]

This is no longer the case after #1240 (use the same git code as fluxd); the git mirroring is done only in *Repo.Start(...), and not ad-hoc.