fix for py/rna api bug:

PyC_UnicodeAsByte(), used for getting python strings as bytes wasnt clearning utf-8 conversion errors.
  this would raise an error when getting an operators filepath.

source/blender/python/generic/py_capi_utils.c

@@ -363,14 +363,17 @@ const char *PyC_UnicodeAsByte(PyObject *py_str, PyObject **coerce)
 		 * chars since blender doesnt limit this */
 		return result;
 	}
-	else if(PyBytes_Check(py_str)) {
+	else {
 		PyErr_Clear();
+
+		if(PyBytes_Check(py_str)) {
 			return PyBytes_AS_STRING(py_str);
 		}
 		else {
 			return PyBytes_AS_STRING((*coerce= PyUnicode_EncodeFSDefault(py_str)));
 		}
 	}
+}
 
 PyObject *PyC_UnicodeFromByte(const char *str)
 {