mysql connector, InterfaceError: Use multi=True when executing multiple statements

Seen on a TravisCI run using the new PyPy 5.8 release, https://travis-ci.org/peterjc/biopython/jobs/241126458 which probably actually down to an update of ``mysql-connector-python-rf``?

```
======================================================================
ERROR: test_server (common_BioSQL.DeleteTest)
Check BioSeqDatabase methods.
----------------------------------------------------------------------
Traceback (most recent call last):
File "/home/travis/build/peterjc/biopython/Tests/common_BioSQL.py", line 616, in setUp
load_database("GenBank/cor6_6.gb")
File "/home/travis/build/peterjc/biopython/Tests/common_BioSQL.py", line 228, in load_database
TESTDB = create_database()
File "/home/travis/build/peterjc/biopython/Tests/common_BioSQL.py", line 205, in create_database
server.load_database_sql(SQL_FILE)
File "/home/travis/build/peterjc/biopython/build/lib.linux-x86_64-2.7/BioSQL/BioSeqDatabase.py", line 306, in load_database_sql
self.adaptor.cursor.execute(sql_line)
File "/home/travis/build/peterjc/biopython/.tox/pypy-nocov/site-packages/mysql/connector/cursor.py", line 555, in execute
"Use multi=True when executing multiple statements")
InterfaceError: Use multi=True when executing multiple statements

```

(and many similar failures).

Probably cause: https://stackoverflow.com/questions/15288594/update-database-with-multiple-sql-statments