Use temp file for invoking python linter

Was using the file on disk instead :-Z
Fixes +11778

package.json

@@ -56,7 +56,7 @@
         "c9"
     ],
     "c9plugins": {
-        "c9.ide.language": "#db81bcc3b7",
+        "c9.ide.language": "#ee9c45925a",
         "c9.ide.language.css": "#be07d72209",
         "c9.ide.language.generic": "#847eb66a89",
         "c9.ide.language.html": "#9be847c0ce",
@@ -91,7 +91,7 @@
         "c9.ide.imgeditor": "#612e75ef4f",
         "c9.ide.immediate": "#a962119bec",
         "c9.ide.installer": "#0fde9f0067",
-        "c9.ide.language.python": "#82e4e924a5",
+        "c9.ide.language.python": "#e6f35d4c4d",
         "c9.ide.language.go": "#3d81cc4a70",
         "c9.ide.mount": "#86c8985f34",
         "c9.ide.navigate": "#1fbb7cd53b",