Remote Runner: do not mask avocado.core.output module

The avocado.core.output module is imported with name `output`
which is then masked by the variable name in the scope of this method.

Small issue that is currently harmless, but it's still better to
avoid those name clashes.
Signed-off-by: NCleber Rosa <crosa@redhat.com>

avocado/core/remote/runner.py

@@ -101,7 +101,7 @@ class RemoteTestRunner(TestRunner):
             return (False, None)
 
     @staticmethod
-    def _parse_json_response(output):
+    def _parse_json_response(json_output):
         """
         Try to parse JSON response from the remote output.
 
@@ -109,7 +109,7 @@ class RemoteTestRunner(TestRunner):
         everything till the end of the dictionary. It supports single-
         line as well as multi-line pretty json output.
         """
-        _result = iter(output.splitlines())
+        _result = iter(json_output.splitlines())
         json_result = ""
         response = None
         for line in _result:    # Find the beginning