- Fixed bug where Postgresql dialect would fail to render an

- Fixed bug where Postgresql dialect would fail to render an
expression in an :class:`.Index` that did not correspond directly
to a table-bound column; typically when a :func:`.text` construct
was one of the expressions within the index; or could misinterpret the
list of expressions if one or more of them were such an expression.
fixes #3174

(cherry picked from commit 79fa69f1f37fdbc0dfec6bdea1e07f52bfe18f7b)