diff -r 5b05ceb24a8d -r 87441497ecaa mercurial/commands.py
--- a/mercurial/commands.py	Mon Mar 11 12:06:13 2013 -0700
+++ b/mercurial/commands.py	Mon Mar 11 12:07:33 2013 -0700
@@ -2960,7 +2960,7 @@
     if opts.get('ignore_case'):
         reflags |= re.I
     try:
-        regexp = re.compile(pattern, reflags)
+        regexp = util.compilere(pattern, reflags)
     except re.error, inst:
         ui.warn(_("grep: invalid match pattern: %s\n") % inst)
         return 1