--- a/mercurial/templater.py	Sat Aug 04 12:29:53 2012 +0200
+++ b/mercurial/templater.py	Sat Aug 04 14:37:17 2012 +0200
@@ -295,6 +295,8 @@
         conf.read(mapfile)
 
         for key, val in conf[''].items():
+            if not val:
+                raise SyntaxError(_('%s: missing value') % conf.source('', key))
             if val[0] in "'\"":
                 try:
                     self.cache[key] = parsestring(val)