convert: check for darcs-2-compatible path

hgext/convert/darcs.py

@@ -32,7 +32,7 b' class darcs_source(converter_source, com'
         if ElementTree is None:
             raise util.Abort(_("Python ElementTree module is not available"))
 
-        if not os.path.exists(os.path.join(path, '_darcs', 'inventory')):
+        if not os.path.exists(os.path.join(path, '_darcs', 'inventories')):
             raise NoRepo("%s does not look like a darcs repo" % path)
 
         self.path = os.path.realpath(path)