superset: Build fails on Postgres DB

Make sure these boxes are checked before submitting your issue - thank you!

• [X ] I have checked the superset logs for python stacktraces and included it here as text if any
• [X ] I have reproduced the issue with at least the latest released version of superset
• [X ] I have checked the issue tracker for the same issue and I haven’t found one similar

Superset version

master (0.25

Expected results)

Build should complete with a Postgres v10 DB

Actual results

Build fails with the following error:

INFO [alembic.runtime.migration] Running upgrade 956a063c52b3 -> 1226819ee0e3, Fix wrong constraint on table columns WARNI [root] Could not find or drop constraint on columns Traceback (most recent call last): File “/usr/local/lib/python3.4/site-packages/sqlalchemy/engine/base.py”, line 1193, in _execute_context context) File “/usr/local/lib/python3.4/site-packages/sqlalchemy/engine/default.py”, line 507, in do_execute cursor.execute(statement, parameters) psycopg2.InternalError: current transaction is aborted, commands ignored until end of transaction block sqlalchemy.exc.InternalError: (psycopg2.InternalError) current transaction is aborted, commands ignored until end of transaction block [SQL: “UPDATE alembic_version SET version_num=‘1226819ee0e3’ WHERE alembic_version.version_num = ‘956a063c52b3’”] (Background on this error at: http://sqlalche.me/e/2j85)

Steps to reproduce

Follow steps in https://github.com/apache/incubator-superset/blob/master/CONTRIBUTING.md for setting up DEV environment.

Note that this build runs fine with branch 0.25.5.