Fix python style.

Author: viirya

python/pyspark/sql/utils.py

@@ -46,7 +46,7 @@ def deco(*a, **kw):
         except py4j.protocol.Py4JJavaError as e:
             s = e.java_exception.toString()
             stackTrace = '\n\t at '.join(map(lambda x: x.toString(),
-                                            e.java_exception.getStackTrace()))
+                                             e.java_exception.getStackTrace()))
             if s.startswith('org.apache.spark.sql.AnalysisException: '):
                 raise AnalysisException(s.split(': ', 1)[1], stackTrace)
             if s.startswith('java.lang.IllegalArgumentException: '):