fix sniffers of the triple format

lib/galaxy/datatypes/data.py

@@ -884,7 +884,7 @@ def regex_line_dataprovider( self, dataset, **settings ):
         dataset_source = dataproviders.dataset.DatasetDataProvider( dataset )
         return dataproviders.line.RegexLineDataProvider( dataset_source, **settings )
 
-    def safe_readlines(self, path, num_lines=1, size=5 * 1024):
+    def __safe_readlines(self, path, num_lines=1, size=5 * 1024):
         """
         Read lines from the start of a file but be sure to restrict the size of
         memory that will be consumed and use proper file handling to ensure file
@@ -895,8 +895,11 @@ def safe_readlines(self, path, num_lines=1, size=5 * 1024):
             lines = start_of_file.splitlines()
             return lines[0:num_lines]
 
+    def safe_readlines(self, path, num_lines=1, size=5 * 1024):
+        return "".join( self.__safe_readlines( path, num_lines, size ) )
+
     def safe_readline(self, path):
-        self.safe_readlines(path)[0]
+        return self.__safe_readlines(path)[0]
 
 
 class GenericAsn1( Text ):