dispatch: restore a dropped shlex import

Add test-dispatch as a place for command parsing and dispatch tests.

tests/test-dispatch

@@ -0,0 +1,15 b''
+#!/bin/sh
+# test command parsing and dispatch
+
+hg init a
+cd a
+echo a > a
+hg ci -Ama -d '0 0'
+
+echo '% [defaults]'
+hg cat a
+cat > $HGRCPATH <<EOF
+[defaults]
+cat = -v
+EOF
+hg cat a

tests/test-dispatch.out

@@ -0,0 +1,4 b''
+adding a
+% [defaults]
+a
+a

mercurial/cmdutil.py

@@ -7,9 +7,9 b''
 
 from node import *
 from i18n import _
-import os, sys, mdiff, bdiff, util, templater, patch, commands
-import atexit, signal, pdb, hg, lock, fancyopts, traceback
-import socket, revlog, version, extensions, errno
+import os, sys, atexit, signal, pdb, traceback, socket, errno, shlex
+import mdiff, bdiff, util, templater, patch, commands, hg, lock
+import fancyopts, revlog, version, extensions
 
 revrangesep = ':'