A fix for the metadata reverting issue seen with PBS job runner.

lib/galaxy/jobs/__init__.py

@@ -274,6 +274,7 @@ class JobWrapper( object ):
         Prepare the job to run by creating the working directory and the
         config files.
         """
+        mapping.context.current.clear() #this prevents the metadata reverting that has been seen in conjunction with the PBS job runner
         # Create the working directory
         self.working_directory = \
             os.path.join( self.app.config.job_working_directory, str( self.job_id ) )
@@ -643,4 +644,4 @@ class NoopQueue( object ):
     def put( self, *args ):
         return
     def shutdown( self ):
-        return
+        return