Merge branch 'ml/filter-branch-no-op-error'

"git filter-branch" learned to use a different exit code to allow
the callers to tell the case where there was no new commits to
rewrite from other error cases.

* ml/filter-branch-no-op-error:
filter-branch: return 2 when nothing to rewrite

diff --combined git-filter-branch.sh
index 98c76ec589b053c112ddc86b6821f2acf17b7ab0,c285fdb90d1a86cd2f360e3ff1768c82a7162fd5..2587a01b9b4fa0344c695cb635e6eed26257e9f8
--- 1/git-filter-branch.sh
--- 2/git-filter-branch.sh
+++ b/git-filter-branch.sh
@@@ -310,7 -310,7 +310,7 @@@ git rev-list --reverse --topo-order --d
        die "Could not get the commits"
  commits=$(wc -l <../revs | tr -d " ")
  
- test $commits -eq 0 && die "Found nothing to rewrite"
+ test $commits -eq 0 && die_with_status 2 "Found nothing to rewrite"
  
  # Rewrite the commits
  report_progress ()
@@@ -627,12 -627,12 +627,12 @@@ the
                                print H "$_:$f\n" or die;
                        }
                        close(H) or die;' || die "Unable to save state")
 -      state_tree=$(/bin/echo -e "100644 blob $state_blob\tfilter.map" | git mktree)
 +      state_tree=$(printf '100644 blob %s\tfilter.map\n' "$state_blob" | git mktree)
        if test -n "$state_commit"
        then
 -              state_commit=$(/bin/echo "Sync" | git commit-tree "$state_tree" -p "$state_commit")
 +              state_commit=$(echo "Sync" | git commit-tree "$state_tree" -p "$state_commit")
        else
 -              state_commit=$(/bin/echo "Sync" | git commit-tree "$state_tree" )
 +              state_commit=$(echo "Sync" | git commit-tree "$state_tree" )
        fi
        git update-ref "$state_branch" "$state_commit"
  fi