http/500 when input data breaks schema rules

[al4]

Handle this gracefully:

[2016-09-27 15:25:25 +0000] [2642] [ERROR] Error handling request /releases/00dc9623-36e5-4869-a58e-edac34c945d9/packages
Traceback (most recent call last):
  File "/usr/share/python/orlo/local/lib/python2.7/site-packages/gunicorn/workers/sync.py", line 135, in handle
    self.handle_request(listener, req, client, addr)
  File "/usr/share/python/orlo/local/lib/python2.7/site-packages/gunicorn/workers/sync.py", line 176, in handle_request
    respiter = self.wsgi(environ, resp.start_response)
  File "/usr/share/python/orlo/local/lib/python2.7/site-packages/flask/app.py", line 2000, in __call__
    return self.wsgi_app(environ, start_response)
  File "/usr/share/python/orlo/local/lib/python2.7/site-packages/flask/app.py", line 1991, in wsgi_app
    response = self.make_response(self.handle_exception(e))
  File "/usr/share/python/orlo/local/lib/python2.7/site-packages/flask/app.py", line 1567, in handle_exception
    reraise(exc_type, exc_value, tb)
  File "/usr/share/python/orlo/local/lib/python2.7/site-packages/flask/app.py", line 1988, in wsgi_app
    response = self.full_dispatch_request()
  File "/usr/share/python/orlo/local/lib/python2.7/site-packages/flask/app.py", line 1641, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "/usr/share/python/orlo/local/lib/python2.7/site-packages/flask/app.py", line 1544, in handle_user_exception
    reraise(exc_type, exc_value, tb)
  File "/usr/share/python/orlo/local/lib/python2.7/site-packages/flask/app.py", line 1639, in full_dispatch_request
    rv = self.dispatch_request()
  File "/usr/share/python/orlo/local/lib/python2.7/site-packages/flask/app.py", line 1625, in dispatch_request
    return self.view_functions[rule.endpoint](**req.view_args)
  File "/usr/share/python/orlo/local/lib/python2.7/site-packages/orlo/user_auth.py", line 42, in wrapped
    return func(*args, **kwargs)
  File "/usr/share/python/orlo/local/lib/python2.7/site-packages/orlo/route_releases.py", line 100, in post_packages
    db.session.commit()
  File "/usr/share/python/orlo/local/lib/python2.7/site-packages/sqlalchemy/orm/scoping.py", line 157, in do
    return getattr(self.registry(), name)(*args, **kwargs)
  File "/usr/share/python/orlo/local/lib/python2.7/site-packages/sqlalchemy/orm/session.py", line 801, in commit
    self.transaction.commit()
  File "/usr/share/python/orlo/local/lib/python2.7/site-packages/sqlalchemy/orm/session.py", line 392, in commit
    self._prepare_impl()
  File "/usr/share/python/orlo/local/lib/python2.7/site-packages/sqlalchemy/orm/session.py", line 372, in _prepare_impl
    self.session.flush()
  File "/usr/share/python/orlo/local/lib/python2.7/site-packages/sqlalchemy/orm/session.py", line 2019, in flush
    self._flush(objects)
  File "/usr/share/python/orlo/local/lib/python2.7/site-packages/sqlalchemy/orm/session.py", line 2137, in _flush
    transaction.rollback(_capture_exception=True)
  File "/usr/share/python/orlo/local/lib/python2.7/site-packages/sqlalchemy/util/langhelpers.py", line 60, in __exit__
    compat.reraise(exc_type, exc_value, exc_tb)
  File "/usr/share/python/orlo/local/lib/python2.7/site-packages/sqlalchemy/orm/session.py", line 2101, in _flush
    flush_context.execute()
  File "/usr/share/python/orlo/local/lib/python2.7/site-packages/sqlalchemy/orm/unitofwork.py", line 373, in execute
    rec.execute(self)
  File "/usr/share/python/orlo/local/lib/python2.7/site-packages/sqlalchemy/orm/unitofwork.py", line 532, in execute
    uow
  File "/usr/share/python/orlo/local/lib/python2.7/site-packages/sqlalchemy/orm/persistence.py", line 174, in save_obj
    mapper, table, insert)
  File "/usr/share/python/orlo/local/lib/python2.7/site-packages/sqlalchemy/orm/persistence.py", line 767, in _emit_insert_statements
    execute(statement, multiparams)
  File "/usr/share/python/orlo/local/lib/python2.7/site-packages/sqlalchemy/engine/base.py", line 914, in execute
    return meth(self, multiparams, params)
  File "/usr/share/python/orlo/local/lib/python2.7/site-packages/sqlalchemy/sql/elements.py", line 323, in _execute_on_connection
    return connection._execute_clauseelement(self, multiparams, params)
  File "/usr/share/python/orlo/local/lib/python2.7/site-packages/sqlalchemy/engine/base.py", line 1010, in _execute_clauseelement
    compiled_sql, distilled_params
  File "/usr/share/python/orlo/local/lib/python2.7/site-packages/sqlalchemy/engine/base.py", line 1146, in _execute_context
    context)
  File "/usr/share/python/orlo/local/lib/python2.7/site-packages/sqlalchemy/engine/base.py", line 1341, in _handle_dbapi_exception
    exc_info
  File "/usr/share/python/orlo/local/lib/python2.7/site-packages/sqlalchemy/util/compat.py", line 202, in raise_from_cause
    reraise(type(exception), exception, tb=exc_tb, cause=cause)
  File "/usr/share/python/orlo/local/lib/python2.7/site-packages/sqlalchemy/engine/base.py", line 1139, in _execute_context
    context)
  File "/usr/share/python/orlo/local/lib/python2.7/site-packages/sqlalchemy/engine/default.py", line 450, in do_execute
    cursor.execute(statement, parameters)
DataError: (psycopg2.DataError) value too long for type character varying(16)
 [SQL: 'INSERT INTO package (id, name, stime, ftime, duration, status, version, diff_url, rollback, release_id) VALUES (%(id)s, %(name)s, %(stime)s, %(ftime)s, %(duration)s, %(status)s, %(version)s, %(diff_url)s, %(rollback)s, %(release_id)s)'] [parameters: <...>]