mercurial/commands.py

--- a/mercurial/commands.py	Sat Mar 16 22:48:22 2013 -0500
+++ b/mercurial/commands.py	Mon Mar 18 19:59:05 2013 -0500
@@ -2972,7 +2972,7 @@
     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