So that we can enable this in jenkins until
Ibc1b0106394d20f5bcf847f37b09d185f26ac9b5 is merged.
Change-Id: Ia704e75bf3767e02d448a6af02530dfc89c9920b
cext: REQUIRE_SQLALCHEMY_CEXT=1
cov: COVERAGE={[testenv]cov_args}
sqlite: SQLITE={env:TOX_SQLITE:--db sqlite}
+ sqlite_file: SQLITE={env:TOX_SQLITE:--db sqlite}
postgresql: POSTGRESQL={env:TOX_POSTGRESQL:--db postgresql}
mysql: MYSQL={env:TOX_MYSQL:--db mysql --db pymysql}
oracle: ORACLE={env:TOX_ORACLE:--db oracle}