Merge branch 'mz/rebase'

* mz/rebase: (34 commits)
  rebase: define options in OPTIONS_SPEC
  Makefile: do not install sourced rebase scripts
  rebase: use @{upstream} if no upstream specified
  rebase -i: remove unnecessary state rebase-root
  rebase -i: don't read unused variable preserve_merges
  git-rebase--am: remove unnecessary --3way option
  rebase -m: don't print exit code 2 when merge fails
  rebase -m: remember allow_rerere_autoupdate option
  rebase: remember strategy and strategy options
  rebase: remember verbose option
  rebase: extract code for writing basic state
  rebase: factor out sub command handling
  rebase: make -v a tiny bit more verbose
  rebase -i: align variable names
  rebase: show consistent conflict resolution hint
  rebase: extract am code to new source file
  rebase: extract merge code to new source file
  rebase: remove $branch as synonym for $orig_head
  rebase -i: support --stat
  rebase: factor out call to pre-rebase hook
  ...

git-parse-remote.sh

@@ -50,3 +50,41 @@ get_remote_merge_branch () {
 	    esac
 	esac
 }
+
+error_on_missing_default_upstream () {
+	cmd="$1"
+	op_type="$2"
+	op_prep="$3"
+	example="$4"
+	branch_name=$(git symbolic-ref -q HEAD)
+	if test -z "$branch_name"
+	then
+		echo "You are not currently on a branch, so I cannot use any
+'branch.<branchname>.merge' in your configuration file.
+Please specify which branch you want to $op_type $op_prep on the command
+line and try again (e.g. '$example').
+See git-${cmd}(1) for details."
+	else
+		echo "You asked me to $cmd without telling me which branch you
+want to $op_type $op_prep, and 'branch.${branch_name#refs/heads/}.merge' in
+your configuration file does not tell me, either. Please
+specify which branch you want to use on the command line and
+try again (e.g. '$example').
+See git-${cmd}(1) for details.
+
+If you often $op_type $op_prep the same branch, you may want to
+use something like the following in your configuration file:
+    [branch \"${branch_name#refs/heads/}\"]
+    remote = <nickname>
+    merge = <remote-ref>"
+		test rebase = "$op_type" &&
+		echo "    rebase = true"
+		echo "
+    [remote \"<nickname>\"]
+    url = <url>
+    fetch = <refspec>
+
+See git-config(1) for details."
+	fi
+	exit 1
+}