Merge pull request #400 from aegypius/suppress-git-output-unless-dokku-trace-is-enabled

Suppress git "detached HEAD" notice output

plugins/git/commands

@@ -8,6 +8,7 @@ git_archive_all() {
     unset GIT_DIR GIT_WORK_TREE
     git clone $DOKKU_ROOT/$APP $TMP_WORK_DIR > /dev/null
     pushd $TMP_WORK_DIR > /dev/null
+    git config advice.detachedHead false
     git checkout $REV > /dev/null
     git submodule update --init --recursive > /dev/null
     find -name .git -prune -exec rm -rf {} \; > /dev/null