Merge pull request #6 from PyMySQL/fix-nested-exception

Exception raised from _mysql should be reraise as is.

MySQLdb/connections.py

@@ -34,6 +34,8 @@ def defaulterrorhandler(connection, cursor, errorclass, errorvalue):
         connection.messages.append(error)
     del cursor
     del connection
+    if isinstance(errorvalue, BaseException):
+        raise errorvalue
     if errorclass is not None:    
         raise errorclass(errorvalue)
     else:

MySQLdb/cursors.py

@@ -214,8 +214,7 @@ class BaseCursor(object):
         except (SystemExit, KeyboardInterrupt):
             raise
         except:
-            exc, value, tb = sys.exc_info()
-            del tb
+            exc, value = sys.exc_info()[:2]
             self.messages.append((exc, value))
             self.errorhandler(self, exc, value)
         self._executed = query
@@ -273,8 +272,7 @@ class BaseCursor(object):
         except (SystemExit, KeyboardInterrupt):
             raise
         except:
-            exc, value, tb = sys.exc_info()
-            del tb
+            exc, value = sys.exc_info()[:2]
             self.errorhandler(self, exc, value)
         qs = '\n'.join([query[:p], ',\n'.join(q), query[e:]])
         if not PY2:

tests/test_MySQLdb_capabilities.py

@@ -92,7 +92,16 @@ class test_MySQLdb(capabilities.DatabaseTest):
 
     def test_ping(self):
         self.connection.ping()
-        
+
+    def test_reraise_exception(self):
+        c = self.cursor
+        try:
+            c.execute("SELECT x FROM not_existing_table")
+        except MySQLdb.ProgrammingError as e:
+            self.assertEqual(e.args[0], 1146)
+            return
+        self.fail("Should raise ProgrammingError")
+
         
 if __name__ == '__main__':
     if test_MySQLdb.leak_test: