diff -r 6e092ea2eff1 -r 15afda349b11 mercurial/templater.py
--- a/mercurial/templater.py	Thu Mar 12 22:59:52 2015 -0400
+++ b/mercurial/templater.py	Fri Mar 13 17:55:04 2015 -0500
@@ -749,7 +749,11 @@
         styles = [styles]
 
     for style in styles:
-        if not style:
+        # only plain name is allowed to honor template paths
+        if (not style
+            or style in (os.curdir, os.pardir)
+            or os.sep in style
+            or os.altsep and os.altsep in style):
             continue
         locations = [os.path.join(style, 'map'), 'map-' + style]
         locations.append('map')