autogen createindex has column objects, but then this crashes when trying to do to_index()

[zzzeek]

    @writer.rewrites(ops.CreateIndexOp)
    def create_index(context, revision, op):
        return [ops.CreateIndexOp(
            op.index_name,
            op.table_name,
            op.columns,
            schema=op.schema,
            unique=op.unique,
            postgresql_concurrently=True
        )]

leads to:

File "/home/classic/dev/alembic/alembic/autogenerate/render.py", line 88, in render_op
    lines = util.to_list(renderer(autogen_context, op))
  File "/home/classic/dev/alembic/alembic/autogenerate/render.py", line 115, in _render_modify_table
    t_lines = render_op(autogen_context, t_op)
  File "/home/classic/dev/alembic/alembic/autogenerate/render.py", line 88, in render_op
    lines = util.to_list(renderer(autogen_context, op))
  File "/home/classic/dev/alembic/alembic/autogenerate/render.py", line 229, in _add_index
    index = op.to_index()
  File "/home/classic/dev/alembic/alembic/operations/ops.py", line 808, in to_index
    idx = schema_obj.index(
  File "/home/classic/dev/alembic/alembic/operations/schemaobj.py", line 157, in index
    *[util.sqla_compat._textual_index_column(t, n) for n in columns],
  File "/home/classic/dev/alembic/alembic/operations/schemaobj.py", line 157, in <listcomp>
    *[util.sqla_compat._textual_index_column(t, n) for n in columns],
  File "/home/classic/dev/alembic/alembic/util/sqla_compat.py", line 256, in _textual_index_column
    raise ValueError("String or text() construct expected")

one side or the other has to be fixed, not sure what that's about.

[sqla-tester]

Mike Bayer has proposed a fix for this issue in the master branch:

Create schema objects fresh from ops https://gerrit.sqlalchemy.org/c/sqlalchemy/alembic/+/2608

[zzzeek]

this is huge and has some implications so let's start 1.6